# Kinetic Energy and Velocity

1. Apr 13, 2017

### aatari

1. The problem statement, all variables and given/known data
Hi Guys, I dont have a particular problem that I need to solve but I need help with understanding a concept. So we agree that irrespective of mass of an object they will both fall at a same rate if there is no air resistance. However, why is it then when we increase the mass of an object, the potential energy increases, which as a result increases the kinetic energy and which would also increase the velocity of that object.

2. Relevant equations
Eg = mgh
Ek = 1/2mv^2

3. The attempt at a solution

2. Apr 13, 2017

### Staff: Mentor

That is false. Kinetic energy is not velocity. It depends on both mass and velocity. Different mass, different KE for the same velocity.

3. Apr 13, 2017

### Vector1962

For an object dropped from rest from a specific height, y = h, the total energy at h, is TE = PE + KE. At y = h, PE = mgh and KE = 0 (rest). So TE = mgh.

The value of TE calculated does not change as the object falls. At any y value along the path, the total energy is the same, this includes the point at y=0. So, at y = 0, TE = PE + KE --> mg0 + 1/2 mv2 = TE = mgh. The mass cancels out which makes the velocity independent of the mass.

4. Apr 13, 2017

### blacksea7

in a simple way...try imagining a bowling ball falling from 1m on your hand vs a tennis ball falling they're pulled at the same speed 9.8m/s just the mass differs the impact on your hand) that velocity is the same just if maybe your friend pushes it down while dropping it it increases the speed..