Question

When a horizontal 'F' acts on object of mass 20 kg, it moves with constant speed. When a force of '3F' is applied on it, it moves with acceleration of 2m/s square . Find "f".​

Answer 1

Answer:

20N

Explanation:

In the given(1st) case, the horizontal force "F" is getting cancelled by the friction (as there is no effective force, a = 0 because of constant velocity)

  ⇒ F = frictional force

When the 3F is applied, mass of 20kg moves with 2 m/s²     (it means, effective force on the mass is  ma = 20*2 = 40 N).

  In this case,

     ⇒ 3F = Friction + Eff. force

     ⇒ 3F = F + 40

    ⇒ 2F = 40

    ⇒ F = 20N

Hence the required value of F is 20N

Answer 2

Given :-

When a horizontal 'F' acts on an object of mass 20 kg, it moves with constant speed. When a force of '3F' is applied to it, it moves with an acceleration of 2m/s square.

To Find :-

Value of F

Solution :-

We know that

F = ma

F = 20 × 2

F = 40 N

Now

3F - F = Force applied

2F = 40

F = 40/2

F = 20 N

Hence

Value of F is 20 N