Question

The diagram shows two blocks P and Q of masses 2 kg and 3 kg respectively connected by a light string passing over a smooth pulley. Block P starts from rest and moves through a distance of 5m on the smooth inclined plane while Q moves downwards. Take the acceleration due to gravity to be 10N/kg.
What is the loss of gravitational potential energy of Q and gain in gravitational potential energy of P?

Answer 1

I worked ou the P.E of block P by the formula Ep=mgh. I got 60 J. But I don't know how to work for block Q?

Answer 2

Ok. If you are going by the energy method, then how much would the block Q move down??

Answer 3

by 2 meters

Answer 4

Nope

Answer 5

Would it move down by 5 metres?

Answer 6

Yes

Answer 7

how how come if the masses are differnt

Answer 8

See, the string is moving 5 m when the block P is moving up along the slope. Therefore, the same length of string would also move down for block Q

Answer 9

Ok. So the loss in P.E would be 150J?

Answer 10

Yes

Answer 11

Thank you!

Answer 12

Welcome