Physics Exam 4

What is a collision?

A short-duration impact between two objects.

What does the duration of a collision depend on?

It depends on the materials of the object. A hard object will have a short contact time while a soft object will have a long one.

What is an impulsive force?

It is a large force exerted during a short time interval.

What is the formula for impulse based on a force vs time curve?

J = average force x change in time 

Momentum points in the same direction as —-?

Velocity

The average force needed to stop an object is —— to the time of the collision.

Inversely proportional. The greater the collision time, the less the force of impact.

What is the formula for impulse and its relation to momentum?

J = average force x change in time

J = p final - p initial 

J = mv final - mv initial 

What is an impulse approximation?

It is when smaller forces are ignored during the brief time of the impulsive force.

What does the area under the curve of a force vs time graph represent?

Impulse/ change in momentum

The forces acting on two balls during a collision are an —/— pair. They have — magnitude in — direction.

action/reaction, equal, opposite 

If an object is only subject to internal forces, what will happen to the total momentum of the system?

There is no change.

What is the law of conservation of momentum?

The total momentum of an isolated system is a constant. Interactions within the system do not change the system’s total momentum.

What conditions must be met for the total momentum of a system to be conserved?

There can be no external forces acting on the system.

What is conserved in an inelastic collision?

momentum, some kinetic energy is transformed