A car of mass 800kg attains a speed of 25m/s in 20secs. The power developed in the engine is?
A
1.25 x 10\(^{4}\)W
B
2.50x 10\(^{4}\)W
C
1.25 x 10\(^{6}\)W
D
2.50 x 10\(^{6}\)W
Verified Correct Answer: A.
Physical Principles & Numerical Solution
- Acceleration, a = \(\frac{\text{v}}{\text{t}}\) = \(\frac{25}{20}\) = 1.25ms\(^{-2}\)
- Force, F = ma = 800 x 1.25 = 1,000N
- Average power = Force \times average velocity = 1000 \(\times \frac{0 + 25}{2}\) = 12,500W = 1.25 x 10\(^4\) W
Source: Myschool Past Questions Archive (Record #60756)