Question

Hanna tosses a ball straight up with enough speed to remain in the air for several seconds.

A: What is the velocity of the ball when it reaches its highest point?

B: What is its velocity 1 s before it reaches it’s highest point?

C: What is the change in its velocity during this 1-s interval?

D: What is its velocity 1 s after it reaches its highest point ?

E: What is the change in velocity during this 1 s interval?

F: What is the change in velocity during the two second interval?

G: what is the acceleration of the ball during any of these time intervals and the moment the ball has zero velocity?

Answer 1

In the free fall motion we have that the acceleration is constant and produced by gravity, this acceleration has a magnitude of 32 ft/s2 or 9.8 m/s2 depending on the units you are working with. This means that every second the speed changes a magnitude of 32 ft/2, the velocity will depend of whether the ball is going upward (positive) or downward (negative).

A) At the highest point the ball stops to start the descend, here v=0 ft/s

B) +32 ft/s. The vector is going up, in the next second the velocity is going to be 0 (negative acceleration)

C) V=vf-vo=0-32=-32 ft/s is the constant change in velocity in projectile motion

D) -32 ft/s. The vector is pointing downward

E) V=vf-vo=-32-0=-32 ft/s is the constant change in velocity in projectile motion, 32 ft/s per second

F) Delta V=vf-vo=-32-32=-72 ft/s

g) gravity acceleration is constant 32 ft/s2 (pointing downward vector)