1. A 56-kg trampoline artist jumps upward from the top of a platform with a vert

Question

1. A 56-kg trampoline artist jumps upward from the top of a platform with a vertical speed of 5 m/s .

Part A

How fast is he going as he lands on the trampoline, 2 m below?

Express your answer to two significant figures and include the appropriate units.

Part B

If the trampoline behaves like a spring of spring constant 5.4×104 N/m , how far does he depress it?

Express your answer to two significant figures and include the appropriate units.

2. A roller-coaster car shown in the figure below is pulled up to point 1 where it is released from rest. Take y = 30 m.

Part A

Assuming no friction, calculate the speed at point 2.

Express your answer to two significant figures and include the appropriate units.

Part B

Calculate the speed at point 3.

Express your answer to two significant figures and include the appropriate units.

3. A skier traveling 11.0 m/s reaches the foot of a steady upward 17 incline and glides 14 m up along this slope before coming to rest.

Part A

What was the average coefficient of friction?

Express your answer using two significant figures.

4. You drop a ball from a height of 2.3 m , and it bounces back to a height of 1.7 m .

Part A

What fraction of its initial energy is lost during the bounce?

Express your answer using two significant figures.

Part B

What is the ball's speed just before the bounce?

Express your answer to two significant figures and include the appropriate units.

Part C

What is the ball's speed just after the bounce?

Express your answer to two significant figures and include the appropriate units.

Part D

Where did the energy go?

Where did the energy go?Which Option is the best ?

The energy "lost" was changed primarily into thermal energy due to friction.

5. In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy without the aid of a pole.

Part A

With what minimum speed must athlete leave the ground in order to lift his center of mass 2.20 m and cross the bar with a speed of 0.75 m/s ?

Express your answer to two significant figures and include the appropriate units.

6. A sled is initially given a shove up a frictionless 28.0 incline. It reaches a maximum vertical height 1.75 m higher than where it started at the bottom.

Part A

What was its initial speed?

Express your answer to three significant figures and include the appropriate units.

The energy "lost" was changed primarily into acoustic energy. The energy "lost" was changed primarily into heat energy. The energy "lost" was changed primarily into chemical energy.

The energy "lost" was changed primarily into thermal energy due to friction.

5. In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy without the aid of a pole.

Part A

With what minimum speed must athlete leave the ground in order to lift his center of mass 2.20 m and cross the bar with a speed of 0.75 m/s ?

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

1]

a] He loses his initial kinetic and potential energy and gains kinetic energy

(1/2) m*(5)^2 + mgh = (1/2)mv^2

v^2 = 5^2 + 2gh

v = sqrt(5^2 + 2*9.8*2)

= 8 m/s

b] His KE gets converted into PE stored in the trampoline

(1/2)mv^2 = (1/2)kx^2

x = v sqrt(m/k)

= 8*sqrt(56/(5.4*10^4))

= 0.26 m Answer

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