Question

Q.2) A force is applied to a mass of 16 kg for 3 seconds. As the force is removed the mass
moves 81 m in 3 seconds. What is the value of the force applied?

Answer 1

Answer:

Since mass moves in 3 s is 81 m when the force removed. Therefore, the mass moves with uniform velocity (no acceleration) for next 3 s. F = 144 N. Thus, the value of the force applied ( in first 3 s) is 144 N.

Answer 2

Answer:

288 N

Explanation:

Let's say force applied = F

Then acceleration ( a ) = (F / 16) m/s^2 [ since F = ma ]

From equation v = u + at , we get :

v = 0 + F/16 × 3 [ since initial velocity is zero and time for which force is applied is 3 sec ]

v = 3F / 16

From equation s = ut + (at^2)/2 , we get :

81 = (0)(3) + [ (3F/16) × (3)(3) ] /2

Thus on solving , we get - F = 288 N.