Question

A block of mass 5 kg is being raised vertically upward by the help of a string attached to it. It rises with an acceleration of 2m/s2. The block rises by 2.5 m .the work done by tension and work done against gravity are respectively

Answer 1

T=mg=5a

T=5(9.5+2)=59N

the force T and the displacement are in the same direction

therefore,the work done by tension

=Ts cos0=59*2.5*1

=147.5J

here s=2.5m,the distance moved by the block

the gravitational force mg and displacement are in the opposite direction

work done against gravity

=-mgs=5*9.8*2.5

=-122.5J