1. Momentum and Force

2. Momentum
Tendency of objects to keep moving in the same direction with the same speed
Comes from mass in motion
Changes come from forces or result in forces

3. Momentum as a Vector Quantity
Vector quantity: has magnitude and direction
ALWAYS depends on direction!

4. Two identical cars pass each other on I- 65
Two identical cars pass each other on I- 65. They are both traveling the speed limit (70 mph). But in order to pass each other, one must be going north and the other must be going south. Compare their momentums.

5. Momentum Equation p=mv p= momentum (kg·m/sec) m= mass (kg)
v= velocity (m/sec)

6. You are riding a skate board on one of the flat areas at Mass Ave Skate Park. Your momentum is 295 kg·m/sec. Use your own weight to determine the speed you are traveling. Is this speed obtainable when traveling on this surface?

7. Force The rate of change of momentum
Quick change in momentum = large forces
His foot is creating the force to change his momentum.

8. Force Equation 𝐹=𝑚 ∆𝑣 ∆𝑡 F= force (N) m= mass (kg)
∆v= change in velocity (m/sec)
∆t= change in time (sec)

9. Use the speed you determined you were going early in the presentation as your initial speed. You go down a ramp and your speed increases to 8 m/sec in 1 second. Using your weight, determine the force that acted upon your body as you went down the ramp.

10. Review! Momentum: moving in same direction with same speed
p=mv
******direction matters!!!
Force: rate of change of momentum
𝐹=𝑚 ∆𝑣 ∆𝑡
******fast change in momentum makes large force!!!