​Lesson Objectives

• Describe Momentum

• Calculate Momentum during an interaction

• Describe how momentum is conserved in a collision

• Momentum: a quantity defined as the product of the mass and velocity of an object

  • Momentum can be described as inertia in motion

• Momentum can be used to help determine how likely an object is to change its motion

  • A large truck is harder to stop than a smaller car

What is Momentum?

• You can calculate the momentum of an object using the mass and velocity

  • The Unit of momentum is kg*m/s

    • m= mass in kilograms

    • v = velocity in m/s

• In momentum equations, we use the letter p to represent momentum, so we can distinguish it from mass

How to Calculate Momentum

• A 120 kg ostrich is running with a velocity of 16 m/s north. What is the momentum of the ostrich?

  • Step 1: Identify the equation that you need

    • p = m ×v

  • Step 2: Identify the variables that you know

    • p =?

    • m=120

    • v = 16

  • Step 3: Plug in the variables and solve

Calculating Momentum Sample Problem 1

• A 6 kg bowling ball is moving at 10 m/s down the alley toward the pins. What is the momentum of the bowling ball?

  • Step 1: Identify the equation that you need

    • p = m ×v

  • Step 2: Identify the variables that you know

    • p =

    • m=

    • v =

Calculating Momentum Sample Problem 2

• A 6 kg bowling ball is moving at 10 m/s down the alley toward the pins. What is the momentum of the bowling ball?

  • Step 1: Identify the equation that you need

    • p = m ×v

  • Step 2: Identify the variables that you know

    • p =?

    • m=6

    • v = 10

  • Step 3: Plug in the variables and solve

Calculating Momentum Sample Problem 2

• A 2.5 kg puppy is running with a velocity of 4.8 m/s south. What is the

  momentum of the puppy?

  • Step 1: Identify the equation that you need

    • p = m ×v

  • Step 2: Identify the variables that you know

    • p =

    • m=

    • v =

Calculating Momentum Sample Problem 3

• A 2.5 kg puppy is running with a velocity of 4.8 m/s south. What is the

  momentum of the puppy?

  • Step 1: Identify the equation that you need

    • p = m ×v

  • Step 2: Identify the variables that you know

    • p = ?

    • m= 2.5

    • v = 4.8

Calculating Momentum Sample Problem 3

• When a moving object hits an object at rest, momentum is transferred from the moving object to the stationary object.

  • The amount that is transferred depends on the types of objects

• While an object's individual momentum may change, the total momentum between the two objects will not change

• The Law of Conservation of Momentum: The momentum of any closed, isolated system does not change

  • It is true regardless of what happens in the collision

What is the Law of Conservation of Momentum?