Stone A is projected vertically upward from ground with speed 40 m/s. Simultaneously stone B is dropped from rest from a point 60 m above the ground. Take g=10 m/s². If they meet after N/2 seconds, find N.
Physics · Kinematics part-3 Relative motion · Relative motion in one dimension
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Question

Stone A is projected vertically upward from ground with speed 40 m/s. Simultaneously stone B is dropped from rest from a point 60 m above the ground. Take g=10 m/s². If they meet after N/2 seconds, find N.

Physics · Kinematics part-3 Relative motion · Relative motion in one dimension

G1 Physics · Accepted Answer

Both have the same downward acceleration, so relative acceleration is zero. Initial closing speed is 40 m/s and separation is 60 m. Thus t=60/40=3/2 s=N/2, giving N=3.