The Following Data Were Collected for Two Springs

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Unit VII: Review

The following data were collected for two springs:

1. What are the spring constants of springs 1 and 2?

2. How much elastic potential energy would be stored

if spring 2 were stretched from 0 to 0.40 meters?

3. How much additional energy would spring 2 store if stretched from 0.40 to 0.80 m?

4. A 1000 kg car is traveling at a constant speed of 30 m/s.

a. How much energy is transferred to internal energy as the car comes to rest?

b. If the car stops in 100 meters, what is the average force applied to the car?

5. A 1.5 kg kitten jumps down from a 2.0 meter high fence.

a. What is the kitten's ∆Eg?

b. What will be the kitten's speed when it reaches the ground?

6. A 50. g dart rests up against a spring that has been compressed 0.050 meters.

a. If 1.25 J of work were required to compress the spring, what is its spring constant?

b. What is the maximum velocity of the dart after the spring has transferred its energy to it?

c. If the dart were fired vertically, what height would it reach?

d. Draw an energy bar graph for the above situation when the dart reaches a height of 1 m.

7. A 60 kg student jumps from the 10 meter platform into the pool below.

a. Use the appropriate mathematical model from the constant acceleration model (kinematics analysis instead of energy analysis) to determine her velocity at impact.

b. How much Ek does she possess at impact?

c. How much force does the water exert on her if she comes to a stop in 2.0 m? How many G's does she experience? (How many times her weight is this force?)

d. What was the change in the Eg of the diver as she climbed to the top of the 10 m platform?

e. Assuming that all of the Eg was converted into Ek, determine the velocity of the diver at impact.

8. A 1500 kg car is traveling at 20 m/s.

a. How much Ek does it have?

b. If the average braking force applied to the car is 6000 N, how far would it travel before it came to a stop? (Draw an energy bar graph of the situation.)

c. If this same average braking force were applied to the car moving at twice the speed, what would be the stopping distance?

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Using the following information, quantitatively rework these questions from Worksheet 3b:

#1d. A spring with k = 250 N/m is compressed 22 cm. When the 750 g cart is 60 cm high on the loop, what is the maximum kinetic energy the cart could have? (1.64 J)

#2a. The coasting car stops 15 m higher than where it started coasting. Find the velocity when it began coasting, assuming no energy is dissipated. (17.2 m/s)

#4b. The compressed spring launches the 80g block with .67 J of energy. Its velocity is .65 m/s when 42 cm high. How much energy has been lost? (0.324 J)

#5b. While sliding 6 m along the surface of the hill, the average friction force on the crate is 200 N. How much energy is dissipated? (1200 J)