Question

A car accelerates from $10m{s}^{-1}$ to $20m{s}^{-1}$ If the mass of car is $500kg$, the work done is

• A. 35 kJ
• B. 57 kJ
• C. 75 kJ
• D. 50 kJ

Answer 1

Answer: (C)

Using work-energy principle, we get
W = $\Delta$ K.E. = $\frac{1}{2}m({\upsilon }_2{}^2-{\upsilon }_1{}^2)=\frac{1}{2}\times 500(20^2-10^2)$ = 250 (400 - 100) = 75000 J = 75 kJ