A ball is projected vertically upward with speed 25 m s⁻¹. Taking g=10 m s⁻², find the distance travelled during the 3rd second, in metre.
Physics · Kinematics Part-1 (one dimension) · Motion under gravity
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Question

A ball is projected vertically upward with speed 25 m s⁻¹. Taking g=10 m s⁻², find the distance travelled during the 3rd second, in metre.

G1 Physics · Accepted Answer

The 3rd second is from t=2 s to t=3 s. The highest point is reached at t = 25/10 = 2.5 s. Hence the turning point lies in the middle of the 3rd second. At t=2 s, upward speed = 25−20 = 5 m s⁻¹. Distance from 2 to 2.5 s = (5+0)(0.5)/2 = 1.25 m. The downward distance from 2.5 to 3 s is also 1.25 m. Total distance = 2.5 m.