alleryA force of 10 N acts on a 2 kg body at rest. After 5 s, the kinetic energy of the body is:
A100 J
B200 J
C500 J
D625 J
Answer & Solution
Correct answer: D. 625 J
1. Acceleration a = F / m = 10 / 2 = 5 m s⁻².
2. Velocity after 5 s: v = a t = 5 × 5 = 25 m s⁻¹.
3. KE = ½ m v² = 0.5 × 2 × 625 = 625 J.
4. Check via W: W = F·s; s = ½ a t² = ½·5·25 = 62.5 m; W = 10 × 62.5 = 625 J. ✓
_Source: syllabus Physics Ch 5, §5.4 Work–Energy applications_
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