Abaseball is thrown by the center fielder (from shoulder level) to home plate where it is caught (on the fly at an equal shoulder level) by the catcher. at what point is the ball's speed at a minimum? (air resistance is negligible)
a) just after leaving the center fielder's hand
b) just before arriving at the catcher's mitt
c) at the top of the trajectory
d) speed is constant during entire trajectory
e) both a and b are correct

C

Explanation:

The speed of the ball will be minimum at the top of the trajectory. Because at the top of the trajectory vertical component of the velocity will be zero and only horizontal component will exit and thus the velocity will be minimum at that point. Hence here option C will be correct.

the device is called “ rocket engine”

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.