Question #1556

A building of 10m high.two objects are projected upwards the 10m high building then the other downwards,with the same unitial velocity of 20m/s at the same time.calculate the time they gona meet and the distances.

Expert's answer

Denote the distance from the ground where two objects should meet as X.

According to the equations of the motion for each object:

X = h - vt - gt2/2

X = 0 +vt - gt2/2

Thus 0 = h - 2vt, t = h/2v = 10/(2*20) = 0.25 [s]

X = 20*0.25 - 10*0.252/2 = 5 - 0.3125 = 4.6875 [m]

According to the equations of the motion for each object:

X = h - vt - gt2/2

X = 0 +vt - gt2/2

Thus 0 = h - 2vt, t = h/2v = 10/(2*20) = 0.25 [s]

X = 20*0.25 - 10*0.252/2 = 5 - 0.3125 = 4.6875 [m]

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