| A | B |
|---|
| Distinguish between mass and momentum. Which is inertia in motion? | Mass is inertia;momentum is inertia in motion. |
| Which has greater mass, the truck or rolling skateboard? | The truck |
| Which has greater momentum, the truck or the rolling skate board? | skateboard |
| Distinguish between impulse and momentum. Which designates a force and which is a force multiplied by time? | Impact designates a force. Impulse=forcextime |
| When the force of impact on an object is extended in time, does the impulse increase or decrease? | Increases |
| Distinguish between impulses and momentum.Which is force x time and which is inertia in motion? | Impulse=force x time;momentum is inertia in motion. |
| Does impulse equal momentum or a change in momentum? | Change in momentum |
| In a car crash, why is it advantageous for an occupant to extend the time the collision takes place? | Greater time=less force |
| For a constant force, suppose the duration of impact on an object doubles. How much does impulse increase? | Doubles |
| For a constant force, suppose the duration of impact on an object doubles. How much does the resulting change in momentum increased? | Doubled. |
| If the time of a car crash is extended by four times, how much does the force of impact change? | reduced one fourth. |
| Why is it advantageous for a boxer to move to the side while throwing a punch and not when the punch is coming at him? | Greater time, less force. Less time greater force. |
| Why does the Pelton Wheel improve over paddle and blades? | It causes a greater change in the fluid's momentum and so provides more impulse. |
| Why does a cannon recoil when fired? | The cannon's momentum must be equal and opposite to the cannonball. |
| What does it mean to say that momentum is conserved? | The momentum before the collision is the same as after. |
| Distinguish between an elastic and inelastic collision. | An elastic collision involves bounces. Objects become distorted and generate heat during an inelastic collision. |
| Imagine you are hovering in space. Your friend bumps into you. If he holds onto you, how fast are you going? | the mass doubles so the speed is halved;2 km/h |
| Is momentum conserved for colliding objects that are moving at angles to one another? Explain. | Yes. Resulting motions follow the vector rules. |
| What is the momentum of an eight kg bowling ball rolling at 2 m/s? | 8 kg x 2 m/s=16 kg x m/s |
| If the bowling ball rolls into a pillow and stops in .5 s, calculate the average force exerted on the pillow. | F=deltamv/t=16kg x m/s/0.5 s=32 N |
| What average force does the pillow exert on the bowling ball. | same |
| What is the momentum of a 50 kg carton that slides at 4 m/s across an icy surface? | 50 kg x 4 m/s=200 kg x m/s |
| The sliding carton skids to a stop on a rough surface in 3 s. Calculate the force of friction it encounters. | F=deltamv/t=(200 kg x m/s)/(3 s)=66.7 |
| What impulse occurs when an average force of 10 N is exerted on a cart for 2.5 s? | 10 N x 2.5 s= 25 Nxs |
| What change in momentum did the cart undergo? | 25 kg x m/s |
| If the mass of the cart is 2 kg and the cart is initially at rest, calculate it's final speed. | 12.5 m/s |
| A 2 kg blob of putty moving at 3 m/s slams into a 2 kg blob at rest. Calculate the speed of the two now stuck together. | 1.5 m/s |
| Calculate the speed of the two blobs if one at rest was four kg. | v=6 kgx m/s/2 kg+4 kg=1 m/s |
