The diagram shows a crane that lifts a load with a mass of 100 kg at a constant speed of 0.4 m/s
for 5 seconds. (g=10 N/kg) Here are 3 statements about this activity:
1 The gain in gravitational potential energy of the load is 2000 J.
2 The tension in the cable at point P is 2000 N.
3 The load accelerates at 10 m/s2
Which statements is/are true?

Answer:

8) A

Speed of lift = 0.4 m/s
Time the load is lifted for = 5s
Distance (height above ground) = 0.4 x 5 = 2 m

Potential energy = m x g x h = 100 x 10 x 2 = 2000J
Hence statement 1 is correct.

In order to lift the load the tension in the cable at point P must be equal to the weight of the load.
Weight of the load = 100 x 10 = 1000N
Hence tension at P = 1000N
So statement 2 is wrong.

The question states that the load is being lifted at a constant speed. This means that there is not change in speed. So there is no acceleration at all.