A deflection, in physics, refers to the change in an object's velocity as a consequence of contact with a surface or the influence of a field. Examples of the former include a ball bouncing off a bat. An object's deflective efficiency can never equal or surpass 100%, for example: a mirror will never reflect the same amount of light cast upon it, though it may concentrate the light, reflected into a narrower beam. on hitting the ground, a ball in free-fall will never bounce back up to the place where it first started to descend. This transfer of some energy into heat or other radiation is a consequence of the theory of thermodynamics, for every such interaction, some energy must be converted into alternative forms of energy or is absorbed by the deformation of the objects involved in the collision. Impulse Reflection
Deep Impact (spacecraft)
Deep Impact was a NASA space probe launched from Cape Canaveral Air Force Station on January 12, 2005. It was designed to study the interior composition of the comet Tempel 1, by releasing an impactor into the comet. At 05:52 UTC on July 4, 2005, the Impactor collided with the comet's nucleus; the impact excavated debris from the interior of the nucleus. Photographs taken by the spacecraft showed the comet to be more dusty and less icy than had been expected; the impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater. Previous space missions to comets, such as Giotto, Deep Space 1, Stardust, were fly-by missions; these missions were able to photograph and examine only the surfaces of cometary nuclei, then from considerable distances. The Deep Impact mission was the first to eject material from a comet's surface, the mission garnered considerable publicity from the media, international scientists, amateur astronomers alike. Upon the completion of its primary mission, proposals were made to further utilize the spacecraft.
Deep Impact flew by Earth on December 31, 2007 on its way to an extended mission, designated EPOXI, with a dual purpose to study extrasolar planets and comet Hartley 2. Communication was unexpectedly lost in September 2013 while the craft was heading for another asteroid flyby; the Deep Impact mission was planned to help answer fundamental questions about comets, which included what makes up the composition of the comet's nucleus, what depth the crater would reach from the impact, where the comet originated in its formation. By observing the composition of the comet, astronomers hoped to determine how comets form based on the differences between the interior and exterior makeup of the comet. Observations of the impact and its aftermath would allow astronomers to attempt to determine the answers to these questions; the mission's Principal Investigator was Michael A'Hearn, an astronomer at the University of Maryland. He led the science team, which included members from Cornell University, University of Maryland, University of Arizona, Brown University, Belton Space Exploration Initiatives, JPL, University of Hawaii, SAIC, Ball Aerospace, Max-Planck-Institut für extraterrestrische Physik.
The spacecraft consists of two main sections, the 372-kilogram copper-core "Smart Impactor" that impacted the comet, the 601 kg "Flyby" section, which imaged the comet from a safe distance during the encounter with Tempel 1. The Flyby spacecraft is 1.7 meters wide and 2.3 meters high. It includes two solar panels, a debris shield, several science instruments for imaging, infrared spectroscopy, optical navigation to its destination near the comet; the spacecraft carried two cameras, the High Resolution Imager, the Medium Resolution Imager. The HRI is an imaging device that combines a visible-light camera with a filter wheel, an imaging infrared spectrometer called the "Spectral Imaging Module" or SIM that operates on a spectral band from 1.05 to 4.8 micrometres. It has been optimized for observing the comet's nucleus; the MRI is the backup device, was used for navigation during the final 10-day approach. It has a filter wheel, with a different set of filters; the Impactor section of the spacecraft contains an instrument, optically identical to the MRI, called the Impactor Targeting Sensor, but without the filter wheel.
Its dual purpose was to sense the Impactor's trajectory, which could be adjusted up to four times between release and impact, to image the comet from close range. As the Impactor neared the comet's surface, this camera took high-resolution pictures of the nucleus that were transmitted in real-time to the Flyby spacecraft before it and the Impactor were destroyed; the final image taken by the Impactor was snapped only 3.7 seconds before impact. The Impactor's payload, dubbed the "Cratering Mass", was 100% copper, with a weight of 100 kg. Including this cratering mass, copper formed 49% of total mass of the Impactor. Since copper was not expected to be found on a comet, scientists could ignore copper's signature in any spectrometer readings. Instead of using explosives, it was cheaper to use copper as the payload. Explosives would have been superfluous. At its closing velocity of 10.2 km/s, the Impactor's kinetic energy was equivalent to 4.8 metric tons of TNT more than its actual mass of only 372 kg.
The mission coincidentally shared its name with the 1998 film, Deep Impact, in which a comet strikes the Earth. Following its launch from Cape Canaveral Air Force Station pad SLC-17B at 18:47 UTC on January 12, 2005, the Deep Impact spacecraft traveled 429 million km in 174 days to reach comet Tempel 1 at a cruising speed of 28.6 km/s. Once the spacecraft reached the vicinity of the comet on July 3, 2005, it separated into the Impactor and Flyby sections; the Impactor used its thrusters to move into the path of the comet, impacting 24 hours at a relative speed of 10.3 km/s. The Impactor delivered 1.96×1010 joules of kinetic energy—the equivalent of 4.7 tons of TNT. Scientists believed that the energy of the high-velocity collision would be sufficient to excavate a crater up to 100 m wide, larger than the bowl of the Roman Colosseum; the size of the crater was still not known one year after the impact. The 2007 Stardust spacecraft's NExT mission determined the crater's diameter to be 150 meters.
Just minutes afte
Kinematics is a branch of classical mechanics that describes the motion of points and systems of bodies without considering the forces that caused the motion. Kinematics, as a field of study, is referred to as the "geometry of motion" and is seen as a branch of mathematics. A kinematics problem begins by describing the geometry of the system and declaring the initial conditions of any known values of position, velocity and/or acceleration of points within the system. Using arguments from geometry, the position and acceleration of any unknown parts of the system can be determined; the study of how forces act on bodies falls within kinetics, not kinematics. For further details, see analytical dynamics. Kinematics is used in astrophysics to describe the motion of celestial bodies and collections of such bodies. In mechanical engineering and biomechanics kinematics is used to describe the motion of systems composed of joined parts such as an engine, a robotic arm or the human skeleton. Geometric transformations called rigid transformations, are used to describe the movement of components in a mechanical system, simplifying the derivation of the equations of motion.
They are central to dynamic analysis. Kinematic analysis is the process of measuring the kinematic quantities used to describe motion. In engineering, for instance, kinematic analysis may be used to find the range of movement for a given mechanism and working in reverse, using kinematic synthesis to design a mechanism for a desired range of motion. In addition, kinematics applies algebraic geometry to the study of the mechanical advantage of a mechanical system or mechanism; the term kinematic is the English version of A. M. Ampère's cinématique, which he constructed from the Greek κίνημα kinema, itself derived from κινεῖν kinein. Kinematic and cinématique are related to the French word cinéma, but neither are directly derived from it. However, they do share a root word in common, as cinéma came from the shortened form of cinématographe, "motion picture projector and camera," once again from the Greek word for movement but the Greek word for writing. Particle kinematics is the study of the trajectory of a particle.
The position of a particle is defined as the coordinate vector from the origin of a coordinate frame to the particle. For example, consider a tower 50 m south from your home, where the coordinate frame is located at your home, such that East is the x-direction and North is the y-direction the coordinate vector to the base of the tower is r =. If the tower is 50 m high the coordinate vector to the top of the tower is r =. In the most general case, a three-dimensional coordinate system is used to define the position of a particle. However, if the particle is constrained to move in a surface, a two-dimensional coordinate system is sufficient. All observations in physics are incomplete without those observations being described with respect to a reference frame; the position vector of a particle is a vector drawn from the origin of the reference frame to the particle. It expresses both the distance of the point from its direction from the origin. In three dimensions, the position of point P can be expressed as P = = x P ı ^ + y P ȷ ^ + z P k ^, where x P, y P, z P are the Cartesian coordinates and ı ^, ȷ ^ and k ^ are the unit vectors along the x, y, z coordinate axes, respectively.
The magnitude of the position vector | P | gives the distance between the origin. | P | = x P 2 + y P 2 + z P 2. The direction cosines of the position vector provide a quantitative measure of direction, it is important to note. The position vector of a given particle is different relative to different frames of reference; the trajectory of a particle is a vector function of time, P, which defines the curve traced by the moving particle, given by P = x P ı ^ + y P ȷ ^ + z P k ^, where
A traffic collision called a motor vehicle collision among other terms, occurs when a vehicle collides with another vehicle, animal, road debris, or other stationary obstruction, such as a tree, pole or building. Traffic collisions result in injury and property damage. A number of factors contribute to the risk of collision, including vehicle design, speed of operation, road design, road environment, driver skill, impairment due to alcohol or drugs, behavior, notably distracted driving and street racing. Worldwide, motor vehicle collisions lead to death and disability as well as financial costs to both society and the individuals involved. In 2013, 54 million people worldwide sustained injuries from traffic collisions; this resulted in 1.4 million deaths in 2013, up from 1.1 million deaths in 1990. About 68,000 of these occurred in children less than five years old. All high-income countries have decreasing death rates, while the majority of low-income countries have increasing death rates due to traffic collisions.
Middle-income countries have the highest rate with 20 deaths per 100,000 inhabitants, accounting for 80% of all road fatalities with 52% of all vehicles. While the death rate in Africa is the highest, the lowest rate is to be found in Europe. Traffic collisions can be classified by general types. Types of collision include head-on, road departure, rear-end, side collisions, rollovers. Many different terms are used to describe vehicle collisions; the World Health Organization uses the term road traffic injury, while the U. S. Census Bureau uses the term motor vehicle accidents, Transport Canada uses the term "motor vehicle traffic collision". Other common terms include auto accident, car accident, car crash, car smash, car wreck, motor vehicle collision, personal injury collision, road accident, road traffic accident, road traffic collision, road traffic incident as well as more unofficial terms including smash-up, pile-up, fender bender; some organizations have begun to avoid the term "accident", instead preferring terms such as "collision", "crash" or "incident".
This is because the term "accident" implies that there is no-one to blame, whereas most traffic collisions are the result of driving under the influence, excessive speed, distractions such as mobile phones or other risky behavior. In the United States, the use of terms other than "accidents" had been criticized for holding back safety improvements, based on the idea that a culture of blame may discourage the involved parties from disclosing the facts, thus frustrate attempts to address the real root causes. Following collisions, long-lasting psychological trauma may occur; these issues may make those. In some cases, the psychological trauma may affect individuals' life can cause difficulty to go to work, attend school, or perform family responsibilities. A number of physical injuries can result from the blunt force trauma caused by a collision, ranging from bruising and contusions to catastrophic physical injury or death. A 1985 study by K. Rumar, using British and American crash reports as data, suggested 57% of crashes were due to driver factors, 27% to combined roadway and driver factors, 6% to combined vehicle and driver factors, 3% to roadway factors, 3% to combined roadway and vehicle factors, 2% to vehicle factors, 1% to combined roadway and vehicle factors.
Reducing the severity of injury in crashes is more important than reducing incidence and ranking incidence by broad categories of causes is misleading regarding severe injury reduction. Vehicle and road modifications are more effective than behavioral change efforts with the exception of certain laws such as required use of seat belts, motorcycle helmets and graduated licensing of teenagers. Human factors in vehicle collisions include anything related to drivers and other road users that may contribute to a collision. Examples include driver behavior and auditory acuity, decision-making ability, reaction speed. A 1985 report based on British and American crash data found driver error and other human factors contribute wholly or to about 93% of crashes. Drivers distracted by mobile devices had nearly four times greater risk of crashing their cars than those who were not. Dialing a phone is the most dangerous distraction, increasing a drivers’ chance of crashing by 12 times, followed by reading or writing, which increased the risk by 10 times.
An RAC survey of British drivers found 78% of drivers thought they were skilled at driving, most thought they were better than other drivers, a result suggesting overconfidence in their abilities. Nearly all drivers, in a crash did not believe themselves to be at fault. One survey of drivers reported that they thought the key elements of good driving were: controlling a car including a good awareness of the car's size and capabilities reading and reacting to road conditions, road signs and the environment alertness and anticipating the behavior of other drivers. Although proficiency in these skills is taught and tested as part of the driving exam, a "good" driver can still be at a high risk of crashing because:...the feeling of being confident in more and more challenging situations is experienced as evidence of driving ability, that'proven' ability reinforces the feelings of confidence. Confidence grows unchecked until something happens -- a near-miss or an accident. An AXA survey concluded Irish drivers are safety-conscious relative to other European drivers.
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An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction. In collisions of macroscopic bodies, some kinetic energy is turned into vibrational energy of the atoms, causing a heating effect, the bodies are deformed; the molecules of a gas or liquid experience elastic collisions because kinetic energy is exchanged between the molecules' translational motion and their internal degrees of freedom with each collision. At any one instant, half the collisions are – to a varying extent – inelastic, half could be described as “super-elastic”. Averaged across an entire sample, molecular collisions are elastic. Although inelastic collisions do not conserve kinetic energy, they do obey conservation of momentum. Simple ballistic pendulum problems obey the conservation of kinetic energy only when the block swings to its largest angle. In nuclear physics, an inelastic collision is one in which the incoming particle causes the nucleus it strikes to become excited or to break up.
Deep inelastic scattering is a method of probing the structure of subatomic particles in much the same way as Rutherford probed the inside of the atom. Such experiments were performed on protons in the late 1960s using high-energy electrons at the Stanford Linear Accelerator; as in Rutherford scattering, deep inelastic scattering of electrons by proton targets revealed that most of the incident electrons interact little and pass straight through, with only a small number bouncing back. This indicates that the charge in the proton is concentrated in small lumps, reminiscent of Rutherford's discovery that the positive charge in an atom is concentrated at the nucleus. However, in the case of the proton, the evidence suggested three distinct concentrations of charge and not one; the formula for the velocities after a one-dimensional collision is: v a = C R m b + m a u a + m b u b m a + m b v b = C R m a + m a u a + m b u b m a + m b where va is the final velocity of the first object after impact vb is the final velocity of the second object after impact ua is the initial velocity of the first object before impact ub is the initial velocity of the second object before impact ma is the mass of the first object mb is the mass of the second object CR is the coefficient of restitution.
In a center of momentum frame the formulas reduce to: v a = − C R u a v b = − C R u b For two- and three-dimensional collisions the velocities in these formulas are the components perpendicular to the tangent line/plane at the point of contact. The normal impulse is: J n = m a m b m a + m b Giving the velocity updates: Δ v a → = J n m a n a → Δ v b → = J n m b n b → A inelastic collision occurs when the maximum amount of kinetic energy of a system is lost. In a inelastic collision, i.e. a zero coefficient of restitution, the colliding particles stick together. In such a collision, kinetic energy is lost by bonding the two bodies together; this bonding energy results in a maximum kinetic energy loss of the system. It is necessary to consider conservation of momentum: (Note: In the sliding block example above, momentum of the two body system is only conserved if the surface has zero friction. With friction, momentum of the two bodies is transferred to the surface that the two bodies ar
Apollo 17 was the final mission of NASA's Apollo program and the last mission as of 2019 in which humans have travelled to and walked on the Moon. Launched at 12:33 a.m. Eastern Standard Time on December 7, 1972, with a crew made up of Commander Eugene Cernan, Command Module Pilot Ronald Evans, Lunar Module Pilot Harrison Schmitt, it was the last use of Apollo hardware for its original purpose. Apollo 17 was the first night launch of a U. S. human spaceflight and the final manned launch of a Saturn V rocket. It was a "J-type mission" which included three days on the lunar surface, extended scientific capability, the third Lunar Roving Vehicle. While Evans remained in lunar orbit in the command and service module and Schmitt spent just over three days on the Moon in the Taurus–Littrow valley and completed three moonwalks, taking lunar samples and deploying scientific instruments. Evans took scientific measurements and photographs from orbit using a scientific instruments module mounted in the service module.
The landing site was chosen with the primary objectives of Apollo 17 in mind: to sample lunar highland material older than the impact that formed Mare Imbrium, investigate the possibility of new volcanic activity in the same area. Cernan and Schmitt returned to Earth on December 19 after a 12-day mission. Apollo 17 is the most recent manned Moon landing and the most recent time humans travelled beyond low Earth orbit, it was the first mission to have no one on board, a test pilot. The mission broke several records: the longest Moon landing, longest total extravehicular activities, largest lunar sample, longest time in lunar orbit. Eugene Cernan, Ronald Evans, former X-15 pilot Joe Engle were assigned to the backup crew of Apollo 14. Engle flew sixteen X-15 flights. Following the rotation pattern that a backup crew would fly as the prime crew three missions Cernan and Engle would have flown Apollo 17. Harrison Schmitt served on the backup crew of Apollo 15 and, following the crew rotation cycle, was slated to fly as Lunar Module Pilot on Apollo 18.
However, Apollo 18 was cancelled in September 1970. Following this decision, the scientific community pressured NASA to assign a geologist to an Apollo landing, as opposed to a pilot trained in geology. In light of this pressure, Harrison Schmitt, a professional geologist, was assigned the Lunar Module Pilot position on Apollo 17. Scientist-astronaut Curt Michel believed that it was his own decision to resign, after it became clear that he would not be given a flight assignment, that mobilized this action. Subsequent to the decision to assign Schmitt to Apollo 17, there remained the question of which crew would become prime crew of the mission. NASA Director of Flight Crew Operations Deke Slayton assigned the backup crew of Apollo 14, along with Schmitt, to the prime crew of Apollo 17; the Apollo 15 prime crew received the backup assignment since this was to be the last lunar mission and the backup crew would not rotate to another mission. However, when the Apollo 15 postage stamp incident became public in early 1972 the crew was reprimanded by NASA and the United States Air Force.
Director of Flight Crew Operations Deke Slayton removed them from flight status and replaced them with Young and Duke from the Apollo 16 prime crew and Roosa from the Apollo 14 prime and Apollo 16 backup crews. Robert F. Overmyer Robert A. Parker C. Gordon Fullerton The insignia's most prominent feature is an image of the Greek sun god Apollo backdropped by a rendering of an American eagle, the red bars on the eagle mirroring those on the flag of the United States. Three white stars above the red bars represent the three crewmen of the mission; the background includes the Moon, the planet Saturn, a galaxy or nebula. The wing of the eagle overlays the Moon, suggesting man's established presence there; the gaze of Apollo and the direction of the eagle's motion embody man's intention to explore further destinations in space. The patch includes, along with the colors of the U. S. flag, the color gold, representative of a "golden age" of spaceflight, to begin with Apollo 17. The image of Apollo in the mission insignia is a rendering of the Apollo Belvedere sculpture.
The insignia was designed with input from the crew. Like Apollo 15 and Apollo 16, Apollo 17 was slated to be a "J-mission," an Apollo mission type that featured lunar surface stays of three days, higher scientific capability, the usage of the Lunar Roving Vehicle. Since Apollo 17 was to be the final lunar landing of the Apollo program, high-priority landing sites that had not been visited were given consideration for potential exploration. A landing in the crater Copernicus was considered, but was rejected because Apollo 12 had obtained samples from that impact, three other Apollo expeditions had visited the vicinity of Mare Imbrium. A landing in the lunar highlands near the crater Tycho was considered, but was rejected because of the rough terrain found there and a landing on the lunar far side in the crater Tsiolkovskiy was rejected due to technical considerations and the operational costs of maintaining communication during surface operations. A landing in a region southwest of Mare Crisium was considered, but rejected on the grounds that a Soviet spacecraft could access t
Newton's laws of motion
Newton's laws of motion are three physical laws that, laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, its motion in response to those forces. More the first law defines the force qualitatively, the second law offers a quantitative measure of the force, the third asserts that a single isolated force doesn't exist; these three laws have been expressed in several ways, over nearly three centuries, can be summarised as follows: The three laws of motion were first compiled by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica, first published in 1687. Newton used them to investigate the motion of many physical objects and systems. For example, in the third volume of the text, Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion. A fourth law is also described in the bibliography, which states that forces add up like vectors, that is, that forces obey the principle of superposition.
Newton's laws are applied to objects which are idealised as single point masses, in the sense that the size and shape of the object's body are neglected to focus on its motion more easily. This can be done when the object is small compared to the distances involved in its analysis, or the deformation and rotation of the body are of no importance. In this way a planet can be idealised as a particle for analysis of its orbital motion around a star. In their original form, Newton's laws of motion are not adequate to characterise the motion of rigid bodies and deformable bodies. Leonhard Euler in 1750 introduced a generalisation of Newton's laws of motion for rigid bodies called Euler's laws of motion applied as well for deformable bodies assumed as a continuum. If a body is represented as an assemblage of discrete particles, each governed by Newton's laws of motion Euler's laws can be derived from Newton's laws. Euler's laws can, however, be taken as axioms describing the laws of motion for extended bodies, independently of any particle structure.
Newton's laws hold only with respect to a certain set of frames of reference called Newtonian or inertial reference frames. Some authors interpret the first law as defining. Other authors do treat the first law as a corollary of the second; the explicit concept of an inertial frame of reference was not developed until long after Newton's death. In the given interpretation mass, acceleration and force are assumed to be externally defined quantities; this is the most common, but not the only interpretation of the way one can consider the laws to be a definition of these quantities. Newtonian mechanics has been superseded by special relativity, but it is still useful as an approximation when the speeds involved are much slower than the speed of light; the first law states that if the net force is zero the velocity of the object is constant. Velocity is a vector quantity which expresses both the object's speed and the direction of its motion; the first law can be stated mathematically when the mass is a non-zero constant, as, ∑ F = 0 ⇔ d v d t = 0.
An object, at rest will stay at rest unless a force acts upon it. An object, in motion will not change its velocity unless a force acts upon it; this is known as uniform motion. An object continues to do. If it is at rest, it continues in a state of rest. If an object is moving, it continues to move without changing its speed; this is evident in space probes. Changes in motion must be imposed against the tendency of an object to retain its state of motion. In the absence of net forces, a moving object tends to move along a straight line path indefinitely. Newton placed the first law of motion to establish frames of reference for which the other laws are applicable; the first law of motion postulates the existence of at least one frame of reference called a Newtonian or inertial reference frame, relative to which the motion of a particle not subject to forces is a straight line at a constant speed. Newton's first law is referred to as the law of inertia. Thus, a condition necessary for the uniform motion of a particle relative to an inertial reference frame is that the total net force acting on it is zero.
In this sense, the first law can be restated as: In every material universe, the motion of a particle in a preferential reference frame Φ is determined by the action of forces whose total vanished for all times when and only when the velocity of the particle is constant in Φ. That is, a particle at rest or in uniform motion in the preferential frame Φ continues in that state unless compelled by forces to change it. Newton's first and second laws are valid only in an inertial reference frame. Any reference frame, in uniform motion with respect to an inertial frame is an in