Editor Staff asked 1 year ago
For a body moving from position Xa to position Xb under a variable force, what is the work done?
(a) W = F * (X2 – X1)
(b) -W = F * (X2 – X1)
(c) W = -F * (X2 – X1)
(d) W = F * (X1 – X2)
This question was posed to me during an interview.
The origin of the question is Work-Energy Theorem for a Variable Force topic in division Work, Energy and Power of Physics – Class 11
Select the correct answer from above options
Interview Questions and Answers, Database Interview Questions and Answers for Freshers and Experience
Editor Staff answered 1 year ago
The correct choice is (a) W = F * (X2 – X1)
The explanation is: Kinetic energy (K) = 1/2 x m x v^2
dK/dt = m*v*dv/dt
Force (F) = m*a
= m*dv/dt
dK/dt = F*v
= m*v*dv/dt
∫
K2
K1
dK/dt =
∫
Xb
Xa
F * dX/dt
∫
K2
K1
dK =
∫
Xb
Xa
F * dX
K2 – K1 = F (X2 – X1)
W = F * (X2 – X1).
