# momentum

## what is momentum

Momentum is a property of a moving object that makes it hard to stop. The more mass it has or the faster its moving, the greater its momentum. Momentum equals mass times velocity and is represented by the equation: Momentum = Mass Velocity Q: What is Codys momentum as he stands at the top of the ramp? A: Cody has no momentum as he stands there because he isnt moving. In other words, his velocity is zero. However, Cody will gain momentum as he starts moving down the ramp and picks up speed. Q: Codys older brother Jerod is pictured in the Figure 1.1. If Jerod were to travel down the ramp at the same velocity as Cody, who would have greater momentum? Who would be harder to stop? A: Jerod obviously has greater mass than Cody, so he would have greater momentum. He would also be harder to stop.

## calculating momentum

To calculate momentum with the equation above, mass is measured in (kg), and velocity is measured in meters per second (m/s). For example, Cody and his skateboard have a combined mass of 40 kg. If Cody is traveling at a velocity of 1.1 m/s by the time he reaches the bottom of the ramp, then his momentum is: Momentum = 40 kg 1.1 m/s = 44 kg m/s Note that the SI unit for momentum is kg m/s. Q: The combined mass of Jerod and his skateboard is 68 kg. If Jerod goes down the ramp at the same velocity as Cody, what is his momentum at the bottom of the ramp? A: His momentum is: Momentum = 68 kg 1.1 m/s = 75 kg m/s

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

factors that determine an objects momentum include its

``````a) mass.

b) velocity.

c) acceleration.

-->  d) two of the above
``````

all objects with mass have momentum.

``````a. true

-->  b. false
``````

to calculate an objects momentum, you would use the formula

``````a) momentum = mass x acceleration.

-->  b) momentum = mass x velocity.

c) momentum = mass/acceleration.

d) momentum = mass/velocity.
``````

which football player has greater momentum?

``````a) ted: mass = 60 kg, velocity = 2.0 m/s

-->  b) todd: mass = 80 kg, velocity = 1.7 m/s

c) tom: mass = 90 kg, velocity = 1.5 m/s

d) tim: mass = 100 kg, velocity = 1.2 m/s
``````

which football players in question 7 have the same momentum?

``````a) ted and todd

b) todd and tom

-->  c) ted and tim

d) none of the above
``````

the faster an object is moving, the harder it is to stop.

``````-->  a. true

b. false
``````

## diagram questions

No diagram questions associated with this lesson