A ball is thrown straight downward from the surface of the moon. Is the maximum height it reaches less than, equal to, or greater than the maximum height reached by a ball thrown upwards on the earth with the same initial speed? Ignore air resistance in both cases

I assume you mean upward

the ball has the same Kinetic energy at release in both cases

(1/2) m V^2 = m g h
so
h = .5 V^2/g

if g is 1/6 that on earth, h will be 6 times higher on the moon

When a ball is thrown straight downward from the surface of the moon, its maximum height will be less than the maximum height reached by a ball thrown upwards on the Earth with the same initial speed.

This is because the force of gravity on the moon is weaker than on Earth. The gravitational force on the moon is approximately 1/6th of the gravitational force on Earth.

When a ball is thrown upwards on Earth, it will experience the force of gravity pulling it downwards, gradually slowing it down until it reaches its maximum height. In the absence of air resistance, the ball will then reverse its direction and fall back to the ground.

On the moon, due to the weaker gravitational force, the ball thrown downward will initially accelerate as it falls, but it will not slow down to the same extent as a ball thrown upwards on Earth. Therefore, it will reach a lower maximum height before falling back to the surface.

To determine whether the maximum height reached by a ball thrown downward on the moon is less than, equal to, or greater than the maximum height reached by a ball thrown upwards on Earth with the same initial speed, we need to consider the relevant physics principles.

When an object is thrown upwards on Earth, it experiences the force of gravity pulling it downwards. As the object rises, its speed decreases until it reaches its highest point, known as the maximum height. At this point, the object momentarily stops moving upward before it starts to fall back down.

On the moon, the gravitational force is weaker compared to Earth due to its lower mass. However, in this scenario, the ball is thrown straight downward, meaning it is initially moving in the same direction as gravity. As a result, the force of gravity acts to accelerate the ball further downward, increasing its speed.

Since the ball thrown downward on the moon gains speed due to gravity, it would have a higher speed compared to the ball thrown upwards on Earth with the same initial speed. This increased speed allows the ball on the moon to reach a higher maximum height compared to the ball thrown upward on Earth. Therefore, the maximum height reached by the ball thrown downward on the moon is greater than the maximum height reached by the ball thrown upwards on Earth with the same initial speed.

It's important to note that this comparison assumes no air resistance in both cases, which allows us to simplify the analysis and focus solely on the effects of gravity.