Q.

A block of mass 1 kg is pushed up a surface inclined to horizontal at an angle of 60 by a force of 10 N parallel to the inclined surface as shown in the figure. When the block is pushed up by 10 m along the inclined surface, the work done against frictional force is [g=10m/s2]     [2024]

1 53 J  
2 5 J  
3 5×103 J  
4 10 J  

Ans.

(2)

fk=μkN=μkmgcos60°

fk=0.1×10×12=0.5 N

Wfriction=-fk·S

                 =-(0.5)×10

Wfriction=-5 J