A block is pushed so that it moves up a ramp at constant speed, from point A nea

Question

A block is pushed so that it moves up a ramp at constant speed, from point A near the bottom of the ramp, to point B near the top of the ramp. Choose a letter for each part and explain you session.

A. Is zero

B. Is less than zero

C.Is greater than zero

D.Cannot be determined

E.Could be positive or negative depending on the choice of coordinate system.

1.The work done on the block by the hand is: explain and choose a letter?

2.The work done on the block by the normal force the ramp is: explain and choose a letter?

3.The work done on the block by friction is: explain and choose a letter?

4.The work done on the block by the gravitational force is: explain and choose a letter?

5.The net work done on the block is : explain and choose a letter?

(Answers in bold please)

Explanation / Answer

1. C. Work is being done by hand against gravity in moving it upwards.

2. A. Normal force always acts perpendicular to motion of the block. Hence W = F.d (where . is dot product) is zero.

3. B. Friction acts against the motion of the block. Hence it does negative work.

4. B. SInce gravitational force acts downwards and block is moving upwards. Hence gravitational force does negative work.

5. C. Because energy of the block is increasing as it moves upwards ( gravitational potential energy).

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