Item 7 A child applies a force F ? parallel to the x -axis to a 10.0-kg sled mov

Question

Item 7

A child applies a force  F?  parallel to the x-axis to a 10.0-kg sled moving on the frozen surface of a small pond. As the child controls the speed of the sled, the x-component of the force she applies varies with the x-coordinate of the sled as shown in figure (Figure 1) . Suppose the sled is initially at rest at x=0. You can ignore friction between the sled and the surface of the pond.

Part A

Use the work-energy theorem to find the speed of the sled at 4.0m .

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Correct

Part B

Use the work-energy theorem to find the speed of the sled at 12.0m .

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Figure 1 of 1

v =   m/s   Item 7 A child applies a force F? parallel to the x-axis to a 10.0-kg sled moving on the frozen surface of a small pond. As the child controls the speed of the sled, the x-component of the force she applies varies with the x-coordinate of the sled as shown in figure (Figure 1) . Suppose the sled is initially at rest at x=0. You can ignore friction between the sled and the surface of the pond. Part A Use the work-energy theorem to find the speed of the sled at 4.0m . v = m/s SubmitMy AnswersGive Up Correct Part B Use the work-energy theorem to find the speed of the sled at 12.0m . v = m/s SubmitMy AnswersGive Up Incorrect; Try Again; 6 attempts remaining Provide FeedbackContinue Figure 1 of 1

Explanation / Answer

Here ,

A)

Work done = area under the Fx - x curve

Using work energy theorum ,

0.5 * m * (v^2 - 0^2 ) = 0.5 * 5 * 4

0.5 * 10 * (v^2 - 0^2 ) = 0.5 * 5 * 4

solving for v

v = 1.414 m/s

the speed of the sled at x = 4 m is 1.414 m/s

B)

at x = 12 cm

Using work energy theorum ,

0.5 * m * (v^2 - 0^2 ) = 0.5 * 10* 8 + 0.5 * 4 * 10

0.5 * 10 * (v^2 - 0^2 ) = 0.5 * 10* 8 + 0.5 * 4 * 10

solving for v

v = 3.464 m/s

the speed of sled at 12 m is 3.464 m/s

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