Physics for Car Collision: Understanding the Role of Momentum, Impulse, Mass, Kinetic Energy and Velocity

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Physics for Car Collision
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Physics for Car Collision
Introduction
Collision can be defined as a situation where two or more objects thwack onto one another
resulting to exchange of different forms of energy between them over a very short period of time.
In the modern society, collisions; deliberate or otherwise are very common especially in
vehicles. Vehicle collision can occur anywhere and any situation such as on highways or parking
lots. They can take place in a variety of forms namely; head-on collision, roll-over, single car
collision onto an object, rear-end collision, or side-impact collision (Petridou and Moustaki
2010, Pp.891-826). This paper focuses in analyzing the physics behind the collision in cars.
Type of Collision
In physics, there exists two types of collision: inelastic and elastic type (Knight, 2017). In elastic
collision, when two objects bang, they bounce away from each other and no energy is lost
through conversion to other forms. On the other hand, when inelastic collision occurs, there is no
bouncing back of the objects and energy from the collision is lost through conversion to other
forms (Duncan and Kennett, 2000). Both types of collisions can occur in vehicles as a result of
the presence of forces acting on cars over a short period of time and presence of other physical
quantities namely; momentum, mass, velocity and impulse by the time of collision. The energies
involved in a collision are kinetic and potential energy.
Role of Momentum, Impulse, Mass, Kinetic Energy and Velocity in a Car Collision
Momentum is a vector quantity used to measure the mass of a body in motion. Mathematically, it
is expressed using the equation P=MV where m is the mass and V is the velocity of the vehicle.
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The mass represents the quantity of matter in the body while velocity represents the rate of
increase of speed as the body or the car is moving. A large vehicle with a mass of 2000kg and
moving at a velocity of 2m/s has the same momentum as a much smaller vehicle with mass
equivalent to 200kg and moving at a velocity of 20m/s. Momentum quantifies the ability of a
body in motion to maintain the same motion when an external force acts on the body over a
given time. The product of the external force and time with which it acts on a body is the
impulse. Impulse totals to the rate of change of momentum. Mathematically the expression is
Ft =∆ p∨Ft =mv−mu where “mv” is the final momentum while “mu” is the initial momentum.
Impulse is the major cause of vehicle accidents (Özkaya, Goldsheyder, and Nordin, 2017).
A vehicle in motion has momentum and to stop such a vehicle an external force has to applied
over time (Impulse). During a collision and depending on the type, the external force can act
either in the same direction as the objects motion or in an opposite direction to the motion of the
vehicle. In a rear-end collision, the force acts in same direction as the motion of the knocked
vehicle resulting to an increase in the velocity of the knocked vehicle and hence its momentum.
On the contrary, in a head-on collision, the external force acts in different direction with motion
of the objects involved resulting to a reduced velocity of the objects and hence reduced
momentum. The vehicle stops when the external force a time that reduces the velocity and hence
the momentum to zero (Knight, 2017).
Kinetic energy refers to the measure of energy in motion. Mathematically, it is expressed using
the expression K= 1
2 mv2 where m is the mass and v the velocity. From the expression, kinetic
energy is directly proportional to mass and is exponentially proportional to velocity (Serway and
Jewett, 2018).
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© <Your Name> 2018