Question

A blocks of mass m is pulled on a rough horizontal surface which has a friction coefficient mew. A horizontal for F is applied which is capable of moving the body uniformly with speed v. Find the work done on the block in time
t by (a) weight of the block, (b) Normal reaction by surface on the block, (c) friction, (d) F.

Answer 1

similarly find the last.

Answer 2

ANSWER

a) W=mg

but here mg makes an angle of 90 with the force (since force is horizontal)

therfore work=0

b) here Normall=mg

which is also at an angle of 90 from force therefore work done by normal=0

c) here lets take the force of friction as f

so f=μN

and N=-mg

therefor f=-umg

and here distance= velocity X time

=vt

therefore

w=-umgt

d) here F=-f

since force=- of friction

so

F=umg

therefore

w=umgvt

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