Question

A force acts for 20 s on a body of mass 20 kg, starting from rest, after which the force ceases and then body describes 50 m in the next 10 s. The value of force will be:

• A. 40 N
• B. 5 N
• C. 20 N
• D. 10 N

Answer 1

The Correct Option is B

The velocity of the body after 20 s of applied force is: \[ S = v t \quad \Rightarrow \quad 50 = v \times 10 \quad \Rightarrow \quad v = 5 \, \text{m/s} \] Using \(v = u + at\), where \(u = 0\): \[ v = a \times 20 \quad \Rightarrow \quad 5 = a \times 20 \quad \Rightarrow \quad a = \frac{1}{4} \, \text{m/s}^2 \] The force is: \[ F = ma = 20 \times \frac{1}{4} = 5 \, \text{N} \]