Single correct option
A car starts from rest and accelerates uniformly to 72 km/h in 10 s. The distance covered by it in this time is
- A. 200 m
- B. 100 m
- C. 720 m
- D. 50 m
Show answer and solution
Answer: (B) 100 m
72 km/h = 20 m/s. Acceleration a = 20/10 = 2 m/s². Distance s = ½at² = ½ × 2 × 100 = 100 m, which is also average speed 10 m/s times 10 s. The trap is 200 m, from multiplying the final speed by the time, and 720 m, from not converting the units.
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