Question

A hammer is thrown upward with a speed of 14 m/s on the surface of planet X where the acceleration due to gravity is 3.5 m/s2 and there is no atmosphere. What is the speed of the hammer after 8.0 s?

Answer 1

Pretty simple

The no atmosphere says that theres no air resistance, making the problem 10 times easier.

If the hammer is thrown upwards, it has a positive inital velocity of 14m/s

Now gravity is trying to pull it downwards so the accelerating is -3.5m/s^2 (closest planet I can think off with this acceleration is Mercury, but thats besides the point)

Anyways we can use kinematic equations to solve that

Vf = vi + at

Vf = 14m/s +(-3.5)(8)

Vf = -14 m/s

So after 8 seconds the ball is going downwards at the same height that you threw it.

answer : -14m/s or you can say 14m/s downwards