# Ek = Eg question

## Homework Statement

you throw a ball directly upward, giving it an initial velocity of 10.0 m/s. neglecting friction, what would be the maximum height of the ball? (explain why you do not need to know the mass of the ball)

## Homework Equations

now the problem itself i understand.

we need Eg=mgh, Ek=1/2mv^2

## The Attempt at a Solution

Ek=Eg
1/2mv^2 = mgh
1/2v^2 = gh
1/2(10.0)^2 = 9.81h
50/9.81 = h
h = 5.1m

i understand that we do not have mass and so it must cancel out, but i am confused as to why we do not need to know the mass?

## Answers and Replies

Cyosis
Homework Helper
What falls faster a feather or a cannon ball? (this problem assumes 0 resistance)

neglecting air friction, neither..
meaning mass doesnt matter

Cyosis
Homework Helper
So you're saying that gravity accelerates all masses in an equal manner. This is correct. What is the one force acting upon the ball after you release it?

only gravity (in this instance because it says to neglect friction)

Cyosis
Homework Helper
Yes, do you understand now why you don't need to know the mass of the ball?

i understand.
thank you