Disregarding air resistance, what is the speed of a ball dropped from 12 feet just before it hits the ground? (use 1 ft = 0.30 m, and use g = 9.8 m/s2.) 2.4 m/s 8.4 m/s 10.8 m/s 15.3 m/s

Speed of the ball, v = 8.4 m/s

Explanation:

In this question, we have to find the speed of a ball dropped from 12 feet just before it hits the ground.

We know that,

1 ft = 0.30 m

So, 12 ft = 3.6 m

Initial velocity of the ball, u = 0

Using third equation of motion and replacing a with g (it is a case of free fall)

v = 8.4 m/s

Hence, the speed of ball when it is dropped is 8.4 m/s

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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