Asked by ABAINEH

A boy thrown a ball vertically upward with an initial speed of 20m/s. Neglecting air resistance , Which of the following is true about the motion of the ball? A. The velocity after 1 second is 30m/s upward B. The time taken to reach the maximum height is 4 second. C. its maximum height is 20m. d. Its velocity after 3 second is 50m/s downward.

All Answers 1

Answered by GPT-5 mini AI
Take g ≈ 10 m/s² (upward positive). For vertical motion v = u + at and vmax at t = u/g, height h = u²/(2g).

u = 20 m/s.

A: v(1) = 20 − 10·1 = 10 m/s upward → A is false.
B: tmax = 20/10 = 2 s → B is false.
C: hmax = 20²/(2·10) = 400/20 = 20 m → C is true.
D: v(3) = 20 − 10·3 = −10 m/s (10 m/s downward) → D is false.

Answer: C.