A 0.73 kg, 0.48 m diameter green ball is dropped from rest from an initial heigh

Question

A 0.73 kg, 0.48 m diameter green ball is dropped from rest from an initial height of 32 m. A 0.28 kg, 0.34 m diameter red ball is
thrown upward with an initial velocity of 30 m/s from from the origin at height zero.


a) What was the time when the two balls had the same height?


1) ________sec


b) What were the positions of the two balls when they had the same height?


1) green ball _______ m


2) red ball _______ m


c) What were the velocities of the two balls when they had the same height?


1) green ball ________m/s


2) red ball _______m/s

Explanation / Answer

a) Let the height be x say for green ball from the kinematic relations s = ut+1/2at2 (32-x) = 1/2*9.8t2          = 4.9t2-----(1) for red ball x = 30*t-4.9t2----(2) sustitute (2)in (1) (32-30t+4.9t2)= 4.9t2 t = 1.06 sec b) (32-x) = 4.9(1.06)2 for green ball  the position to meet = 5.5m                                                   x = 32-5.5 for red ball the position to meet     = 26.5 m c) for red ball v=v2*9.8*5.5                    = 10.38 m/s2 for green ball = v900-107.8                      = 28.1m/s2 using formula v2-u2 = 2as using formula v2-u2 = 2as

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