2a. From the top of a tall building, you throw one ball straight up with a speed

Question

2a. From the top of a tall building, you throw one ball straight up with a speed of vo and one ball straight down with a speed Vo. (i)Which ball has the greater speed when it reaches the ground? (ii)Which ball gets to the ground first? Which ball has a greater displacement when it reaches the ground? (iv)Which ball has travelled a greater distance when it reaches the ground? b. A pitched baseball was released from the pitcher's hand at a speed of 45.0 m/sec. If the pitcher was in contact with the ball over a distance 1.5 m and produced a constant acceleration, (i) what acceleration did he give the ball, and (ii) how much time did it take him to pitch it?

Explanation / Answer

I am answering first question (all parts).

(a) when a ball returns to the original position from where it was thrown, it has the same speed as initial. Thus, even for ball which was thrown up, when it reaches the building level, it has same speed v0.

Therefore, both balls will have same speed when they reach ground.

(b) The ball which is thrown straight down will reach the ground first.

As for the ball which was thrown up, it takes some time to reach to the building level first and then to the ground.

(c) Displacement is the straight line distance between initial and final positions.

For both balls, initial (the building) and final (ground) positions are same, thus, both balls have equal displacements.

(d) The ball which was thrown up traveled more distance than the ball which was thrown downwards.

The ball which was thrown up, traveled first to some maximum height, then returned to building and then to ground.

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