Momentum, Impulse, and Collision Principles

Momentum

The amount of motion an object has; it depends on how heavy it is and how fast it's going.

Momentum Formula

p=mv

Momentum Unit

kg·m/s

Impulse

A force applied over time that changes an object's momentum.

Impulse Formula

J=FΔt

Impulse Unit

N·s (Newton-seconds) or Kg·m/s (kilogram-meter per second)

Force

A push or pull that can change an object's motion.

Force Unit

Newton (N)

Collision

When two or more objects bump into each other, it often involves a momentum transfer.

Elastic Collision

A collision where objects bounce off each other and don't lose any energy.

Elastic Collision Example

Billiard balls colliding.

Inelastic Collision

A collision where objects stick together or lose some energy.

Inelastic Collision Example

Car crash.

Explosion

When something breaks apart suddenly and pieces move in different directions. Kinetic Energy is not last its usually gained.

Conservation

The idea that something (like momentum) stays the same in a closed system, even if things inside it move or change.

What kind of objects have momentum

all moving objects

How can you change in Momentum and whats the easiest way?

Change the object's velocity (accelerate or decelerate), which is easier.

Change the mass of an object.

What is the difference between "impulse" and "change in momentum?"

They're basically the same thing—impulse causes the change in momentum.

How can you maximize the impulse/change in momentum? (two answers)

Apply a bigger force.

Apply the force for a longer time.

Relationship between Impulse and Time of Impact

More time = less force

Relationship between Impulse and Force of Impact

More force = less time needed.

So how can you control the force of impact?

By increasing the time of impact (e.g., using airbags, slowing down gradually).

Why are large, fast objects harder to stop than small, slow ones?

They have more momentum because of their size and speed.

What does it mean to say that momentum is conserved in a system?

The total momentum stays the same unless an outside force acts on it.

Compared with falling on a stone floor, a coffee mug may not break when it falls on a carpeted floor because...

The carpet makes the stop take longer, so there's less force.

When two pool balls in an isolated system collide, the overall momentum of the system...

Stays the same before and after the collision.

Protective Measures for Reducing Momentum

Seatbelts in cars, airbags in cars, parachutes.

Why do players follow through with their swing when they hit the ball?

To keep applying force for longer, which increases the impulse and sends the ball farther.

Why do airplanes need such a long landing strip?

So they can slow down gradually, with less force.