A stone is thrown horizontally from a 45m tall cliff with a velocity of 40m/s. Calculate the position of the stone after 4 seconds and velocity of the stone after 2 seconds

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

because if the tool that you are using is not balanced it there would be false mass.

conservation of mass

mass before something happens = mass afterwards