# Momentum.

## Presentation on theme: "Momentum."— Presentation transcript:

Momentum

Momentum and Sports "Going into the all-star break, the Chicago White Sox have the momentum." "Chicago Bears Gaining Momentum." "You have the momentum; the critical need is that you use that momentum and bury them in this third quarter." – A quote from a coach trying to pump up his team!! What do all these phrases have in common? MOMENTUM

Momentum is commonly used in sports. A team that has the
momentum is on the move and is going to take some effort to stop. Momentum refers to the quantity of motion that an object has. A sports team which is "on the move" has the momentum. An object in motion ("on the move") then has momentum.

What is Momentum? Momentum can be defined as “mass in motion.”
All objects have mass; so if an object is moving, then it has momentum - it has its MASS IN MOTION. The amount of momentum which an object has is dependent upon two variables… Mass and Velocity In other words, how much stuff is moving and how fast the stuff is moving

How can you remember?

Equation Momentum = mass * velocity p=m*v Units??
kgm/s What is the momentum of a 60-kg halfback moving eastward at 9 m/s? p=(60kg)(9m/s) p=540kgm/s

p=mv The equation illustrates that momentum is directly proportional to an object's mass and to the object's velocity. An object has a large momentum if it has a large mass or a large velocity, and both variables are of equal importance in determining the momentum of an object.

EXAMPLE Consider a Mack truck and a roller skate moving down the street at the same speed. Which will have a greater momentum? The considerably greater mass of the Mack truck gives it a considerably greater momentum Consider that the same Mack truck is at rest, but the roller skate is moving. The roller skate. Anything at rest has a momentum of “0”. It is not an “mass in motion.”

Impulse To stop such an object, it is necessary to apply a…
Force AGAINST To stop such an object, it is necessary to apply a force against its motion for a given period of time

The more momentum an object has, the harder that is to stop It would require a greater amount of force or a longer amount of time (or both) to bring an object with more momentum to a halt.

This is called an impulse
Impulse=change in momentum or Ft=Δmv

ESPN Video Questions 1. Explain why the goal posts have padding around their base. The padding will increase the time required to stop and decrease the force.

2. A 90 kg football player is moving at 7m/s
2. A 90 kg football player is moving at 7m/s. Calculate the force required to stop him in .4 seconds; in .2 seconds; in .1 seconds. Ft=Δmv F= Δmv/t F=(90)(7)/(.4) F=1575N

3. Examine the inside of a football helmet
3. Examine the inside of a football helmet. How is the helmet constructed so that the player’s head will have more time to stop during a collision? Why do we want to give the head more time to stop? There is space in the interior of the helmet for the head to move, thereby increasing the time.

4. List safety features in cars which lengthen the time during a collision in order to decrease the maximum force during that collision.