An object of mass \(7 \mathrm{~kg}\) is moving at a constant velocity of \(20 \mathrm{~ms}\). Determine the kinetic energy.
A. \(22.2 \mathrm{KJ}\)
B. \(140.0 \mathrm{KJ}\)
C. \(1.4 \mathrm{KJ}\)
D. \(562.5 \mathrm{KJ}\)
Correct Answer: C
Explanation
\(m=75 k g, v=20 \mathrm{~ms}^{-1}\)
K.E. \(=\frac{1}{2} m v^2\)
\(=\left(\frac{1}{2} \times 7 \times 20^2\right) \mathrm{J}\)
\(=\left(\frac{1}{2} \times 7 \times 400\right) \mathrm{J}\)
\(=1400 \mathrm{~J}\)
\(=\left(\frac{1400}{1000}\right) \mathrm{kJ}=1.4 \mathrm{~kJ}\)
