Questions about vertical projectile motion (two objects moving)

In this video you will solve more questions about vertical projectile motion. This time two objects are moving in opposite direction or in the same.

QUESTION 1 (NOV 14)

A ball, A, is thrown vertically upward from a height, h, with a speed of 15 m/s.
AT THE SAME INSTANT, a second identical ball, B, is dropped from the same height as ball A as shown in the diagram below. (See minute 00:50 for picture)
Both balls undergo free fall and eventually hit the ground.
1.1 Explain the term free fall.
1.2 Calculate the time it takes for ball A to return to its starting point.
1.3 Calculate the distance between ball A and ball B when ball A is at its maximum height.
1.4 Sketch a velocity-time graph in the ANSWER BOOK for the motion of ball A from the time it is projected until it hits the ground.
Clearly show the following on your graph:
• The initial velocity
• The time it takes to reach its maximum height
• The time it takes to return to its starting point

QUESTION 2 (JUNE 16)

Ball A is projected vertically upwards from the ground, near a tall building, with a speed of 30 m/s. Ignore the effects of air friction.

2.1 Explain what is meant by a projectile.
2.2 Calculate:
2.2.1 The total time that ball A will be in the air
2.2.2 The distance travelled by ball A during the last second of its fall.
2.3 TWO SECONDS after ball A is projected upwards, ball B is projected vertically upwards from the roof of the same building. The roof the building is 50 m above the ground. Both balls A and B reach the ground at the same time. Refer to the diagram below. Ignore the effects of air friction.
Calculate the speed with which ball B was projected upwards from the roof.
2.4 Sketch velocity-time graphs for the motion of both balls A and B on the same set of axes. Clearly label the graphs for balls A and B respectively.
Indicate the following on the graphs:
(a) Time taken by both balls A and B to reach the ground
(b) Time taken by ball A to reach its maximum height