Physics - Module 3 - Newtons Laws and Motion Flashcards
Explosions
An explosion can cause two (or more) objects to fly apart. There is a gain in kinetic energy due to the energy of the explosion. Total momentum is conserved.
(For two objects, they must gain equal and opposite momentum along the same straight line)
Inelastic collision
In an inelastic collision, total kinetic energy is not conserved.
(In all collisions, total energy and total momentum are conserved)
Elastic collision
In an elastic collision, total kinetic energy is conserved.
(In all collisions, total energy and total momentum are conserved)
State principle of conservation of linear momentum
For any collision, the total initial momentum is equal to the total final momentum if there are no external forces (or in a closed system).
Whats the meaning of the area under force time graph
Impulse equals the area under the force time graph.
Impulse
Impluse is the product of force and the time for which the force acts.
Units of impulse are Ns
(Base units Ns = kg.m.s-2s = kg.m.s-1)
Describe the two forces in a Newton’s third law pair
In fact there are two Newton’s 3rd law pairs of forces in this situation.
• The Earth (body A) exerts a force of gravity W on mass m (body B). Mass m exerts an equal and opposite force of gravity on the Earth upwards.
• The surface exerts a contact force N on the mass m upwards. Mass m exerts an equal but opposite contact force on the surface downwards.
Momentum
P = Mass x Velocity
Newtons third law
If body A exerts a force on body B then body B exerts an equal and opposite force on body A of the same type.
Newtons second law(F = M x A)
The rate of change of momentum of a body is equal to (or proportional) to the resultant force and in the same direction.
Newtons first law
A body will remain at rest or continue moving in a straight line at constant velocity unless acted on by a resultant force.
