Week

Momentum

Objective

Student will:Study Impulse and Momentum in one dimension

Cornell Notes (1/3)

Momentum: “inertia in motion” -A vector

Questions1) How would you

describe momentum?

Momentum (Kg∙m/s) = Mass (kg) x Velocity (m/s)

Cornell Notes (1/1)

Impulse: A force exerted over a time interval that causes a change in an object’s momentum. -Is a vector

J = FΔt = mΔvImpulse (Kg∙m/s) = Force (N) x

Time(s)= mass (kg) x change in

velocity (m/s)

Questions

1) How does an airbag work?

Cornell Notes (1/5)

Example: ImpulseAssume a bullet travels with a mass of

15 grams at 400 m/s and hits the Hulk. The bullet’s velocity drops to 0 m/s. Calculate the force’s magnitude required to stop the bullet in .5 seconds.

Cornell Notes (2/5)Given:

m = 15 g = 0.015 kg

vi = 400 m/s

vf = 0 m/st = 0.5 s

Unknown: F = ?

Steps1) Define

Assume a bullet travels to the right with a mass of 15 grams at 400 m/s and hits the Hulk. Calculate the force’s magnitude required to stop the bullet in .5 seconds.

Magnitude only

Cornell Notes (3/5)Choose an equation or situation:

Rearrange the equation to isolate the unknown:

2) Plan

What is the unit of the left hand side?

Cornell Notes (4/5)Substitute the values into the equation and solve

3) Calculate

�⃗�=−12�⃗�=−12𝑁

Negative number tells you the direction

Cornell Notes (5/5)The Hulk would exert a force of 12 N on the bullet to stop it in .5 seconds.

Question: If the Hulk stops the bullet in 0.01 seconds instead, what is the Force then?

4) Evaluate

Extension