A force of 6N acts horizontally on a stationary mass of 2kg for 4s. The kinetic energy gained by the mass is _________
A
366j
B
240j
C
144j
D
90j
Verified Correct Answer: C.
Physical Principles & Numerical Solution
F = 6N, m = 2kg, t = 4s, u = 0 (stationary or at rest)
K.E = \(\frac{1}{2}\)mv\(^2\)
F = \(\frac{\text{mv}}{\text{t}}\)
from rest
K.E = \(\frac{1}{2}m(\frac{\text{Ft}}{\text{m}})^2\) = \(\frac{1}{2}\) x 2 x (\(\frac{6 \times 4}{2})^2\) = 12\(^2\) = 144J.
Source: Myschool Past Questions Archive (Record #55249)