Work, Power & Energy Exam Review Packet A block of 1 kg mass is pulled from rest in the horizontal x-direction with a displacement dependent force F(x) = 3x+3.

1. The change in kinetic energy in moving the block a distance of 2 meters

would be

2. The velocity of the block after traveling a distance of 2 meters would be ------------------------------------------------------------------------------------------------------------

3. A force of 32 Newtons is applied to accelerate a 2.0 kg block from rest along a horizontal surface. The frictional force between the block and the surface is 22 Newtons. What is the work done by the frictional force in 12 seconds?

4. A baseball outfielder throws a baseball of mass 0.17 kg at a speed of 45 m/s and initial angle of 30°. What is the kinetic energy of the baseball at the highest point of the trajectory?

5. A 90-kg man runs up a flight of stairs, rising 3.0 m in a time of 5.0 s. What average power did he supply?

6. A spring with spring constant k = 500 N/m is extended 12 cm from its equilibrium position. A spring with 6.0 cm extension from equilibrium will have the same potential energy as the first spring if it has what spring constant?

F"M"="1kg"

7. A 5.0-kg block slides down a plane (inclined at 30° with the horizontal) at a

constant speed of 4.0 m/s. At what rate is the gravitational force on the block doing work? (answer is in Watts/Power)

8. A student drops a 700-g ball from 5.0 m high. It rebounds to 3.75 m. How much energy is lost?

9. A 2.5-kg block situated on a frictionless incline is connected to a light spring (k = 700 N/m), as shown. The block is released from rest when the spring is unstretched. The pulley is frictionless and has negligible mass. What is the speed of the block when it has moved 0.25 m down the plane?

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10. An object of mass 1.5 kg experiences a force that is associated with the potential energy function U(x) =

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−2x 2 + 7x + 4 , where U is in joules and x is in meters. a. On"the"axes"below,"sketch"the"graph"of"U(x)"versus"x."

"

"b. Determine"the"force"associated"with"the"potential"energy"function"

given"above."""""

c. Find"any"point(s)"of"equilibrium"during"the"interval"0m"<"t"<"6m?""""""

d. If"the"particle"is"released"from"rest"at"x"="1"m,"i. what"is"the"maximum"speed"reached"by"the"particle?"

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ii. what"is"the"farthest"displacement"from"the"origin"the"particle"will"reach?"

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iii. will"the"particle"ever"return"to"the"origin"(x=0)?"Justify"your"answer."

U(J)"

x"(m)"0"""""""""1"""""""""""2""""""""""3""""""""""4""""""""""5""""""""""6"

10.

A"0.20"kg"object"moves"along"a"straight"line."The"net"force"acting"on"the"object"varies"with"the"object's"displacement"as"shown"in"the"graph"above."The"object"starts"from"rest"at"displacement"x"="0"and"time"t"="0"and"is"displaced"a"distance"of"20"m."Determine"each"of"the"following."

a. The acceleration of the particle when its displacement x is 6 m. b. The time taken for the object to be displaced the first 12 m. c. The amount of work done by the net force in displacing the object the first 12 m. d. The speed of the object at displacement x = 12 m. e. The final speed of the object at displacement x = 20 m.