**Chapter 11 Practice 2**

A package of mass m is released from rest at a warehouse loading dock and slides down the h = 2.4 m - high, frictionless chute to a waiting truck. Unfortunately, the truck driver went on a break without having removed the previous package, of mass 2m, from the bottom of the chute.

Suppose the packages stick together. What is their common speed after the collision?

Suppose the collision between the packages is perfectly elastic. To what height does the package of mass m rebound?

2.3 m/s

27 cm

A 40.0 kg archer, standing on frictionless ice, shoots a 200 g arrow at a speed of 100 m/s . What is the recoil speed of the archer?

.5 m/s

Dan is gliding on his skateboard at 4.00 m/s . He suddenly jumps backward off the skateboard, kicking the skateboard forward at 8.00 m/s (as measured by an observer on the ground). Dan's mass is 40.0 kg and the skateboard's mass is 6.00 kg . How fast is he going when his feet hit the ground?

3.4 m/s

Two ice skaters, with masses of 50.0 kg and 85.0 kg , are at the center of a 60.0 m -diameter circular rink. The skaters push off against each other and glide to opposite edges of the rink. If the heavier skater reaches the edge in 10.0 s , how long does the lighter skater take to reach the edge?

5.88 s

A 20 g ball of clay traveling east at 8.0 m/s collides with a 80 g ball of clay traveling north at 2.0 m/s. What is the speed and direction of the resulting 100 g ball of clay?

2.3 m/s

45 deg

A 27.0 g ball is fired horizontally with initial speed v0 toward a 110 g ball that is hanging motionless from a 1.10 m -long string. The balls undergo a head-on, perfectly elastic collision, after which the 110 g ball swings out to a maximum angle θmax = 52.0 .

7.3 m/s

A two-stage rocket is traveling at 1210m/s with respect to the earth when the first stage runs out of fuel. Explosive bolts release the first stage and push it backward with a speed of 40m/s relative to the second stage after the explosion. The first stage is three times as massive as the second stage. What is the speed of the second stage after the separation?

1240 m/s

A rocket in deep space has an empty mass of 230 kg and exhausts the hot gases of burned fuel at 2500 m/s. What mass of fuel is needed to reach a top speed of 4000 m/s?

909 kg

A rocket in deep space has an exhaust-gas speed of 2000 m/s. When the rocket is fully loaded, the mass of the fuel is five times the mass of the empty rocket. What is the rocket's speed when half the fuel has been burned?

1078 m/s

A 2.5 kg ball moves east at a speed of 5.5 m/s. It collides with 3.5 kg ball at rest, resulting in an glancing collision. If the 3.5 kg ball leaves at an angle of 40 degrees North of east at a speed of 2.4 m/s. What is the speed and direction of the 2.5 kg ball after the collision?

3.64 m/s

36.4 deg S of E

If the speed of the 3.5 kg ball was 2.4 m/s and it was an elastic collision, what would the speed of the 2.5 kg ball be?

4.71 m/s

and the directions?

3.5 is 58.4 NofE

2.5 is 37.4 SofE

"Why does the third piece emerge from the right end in the Stop and Think 11.5?"

6 g right at v,

4 g left at 2v

third?

"How is an explosion like a backwards inelastic collision?

"The total momentum of a collision is conserved. But why does that mean the momentum in each direction is conserved?

"I'm still having trouble with conservation of momentum and how to calculate it"

"In (Figure 1), what value of Fmax gives an impulse of 6.6 Ns?"