WAEC Physics 2013 Objective — Question 9
Question 9 of 50 from the West African Examinations Council (WAEC) Physics 2013 Objective paper, with the correct answer and a full explanation.
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Use the following information to answer questions 9 and 10. A body of mass 20g projected vertically upwards in vacuum returns to the point of projection after 1.2s. [g=10ms⁻²] Calculate the speed of projection.
- A. 0.6ms⁻¹
- B. 1.2ms⁻¹
- C. 6.0ms⁻¹Correct
- D. 12.0ms⁻¹
Explanation
Time of flight T = 1.2s, so time to reach maximum height t = T/2 = 0.6s. Using v = u − gt with v=0 at max height: 0 = u − (10)(0.6), so u = 6.0ms⁻¹.
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