Question 3
Work, Energy and PowerA 500 kg car which was initially at rest travelled with an acceleration of 5 m s−2, its kinetic energy after 4 seconds was
- A.105 J
- B.2.5 × 103 J
- C.2 × 103 J
- D.5 × 103 J
- E.5 × 105 J
Show the answer and explanation
Answer: A (105 J)
Explanation
After 4 s, v = at = 5 × 4 = 20 m s−1. KE = ½mv² = ½ × 500 × 400 = 100 000 J = 105 J.