Question

A block of mass 5 kg is placed on another block
of mass 10 kg. A force 60 N is acting on the 5 kg
block in horizontal direction if both the blocks
move together, then frictional force on 5 kg is
(g = 10 m/s)
​

Answer 1

Answer:

Coefficient of Friction Not given in question

F = u N

N = Normal Reaction

N = 50

Answer 2

The frictional force acting on the block of mass 5 kg is 40N.

A block of mass 5 kg is placed on another block of mass 10 kg. A force 60 N is acting on the 5 kg block in horizontal direction.

If both the blocks move together, then frictional force on 5 kg is ...

let both blocks move together with an acceleration a.

from Newton's 2nd law of motion,

Fnet = Total mass × acceleration

⇒60 N = (5 + 10)kg × a

⇒a = 60/15 = 4 m/s²

now draw free body diagram of each of them.

from free body diagram of block of mass 5kg,

F - fr = ma

here, F = 60 N , m = 5 kg , a = 4 m/s²

⇒60 - fr = 20

⇒fr = 40 N

Therefore the frictional force acting on the block of mass 5 kg is 40N.