# A block of mass 2kg is slided on a rough surface at t=0,if its speed is 2m/s. It stops after covering a distance of 20cm because of the friction exerted by the surface on it. Calculate the work done

1
by pruthvin

2014-11-18T23:45:22+05:30

### This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
There is only one force acting on the block.

The work done on the block of mass 2 kg by the friction force F in stopping it from a velocity of 2 m/s through a displacement S = 20 cm is:  W

v² - u² = 2 a S,      v = 0     =>   - u² = 2 a S
=> -1/2  m u² = m a S
=>  -1/2 m u² = F S = W

W = - kinetic energy at  t = 0
= - 1/2 *2  * 2² = - 4 Joules.
Work done is negative because the block moved against the force. The direction of force and displacement of the block are opposite.