A 5 kg block is pulled vertically upward by constant force 90 N from rest. After 2 s, a 3 kg part breaks off and falls freely. Find the separation between the two parts when the 3 kg part hits the ground, in metres.
Physics · Newtons law of motion and Friction · newton second law and problem based on it
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Question

A 5 kg block is pulled vertically upward by constant force 90 N from rest. After 2 s, a 3 kg part breaks off and falls freely. Find the separation between the two parts when the 3 kg part hits the ground, in metres.

Physics · Newtons law of motion and Friction · newton second law and problem based on it

G1 Physics · Accepted Answer

Initially a=(90-50)/5=8 m s⁻², so after 2 s the block is 16 m high and moving at 16 m s⁻¹. The 3 kg part returns to ground 4 s later. The remaining 2 kg part has acceleration (90-20)/2=35 m s⁻² and rises to 360 m above ground at that instant. Separation=360 m.