Question

A rock is suspended 320 m above ground. Was the mass of the object needed to calculate the approximate speed with which the rock hits the ground?

Yes, because K.E.=1/2mv^2
No, because g=9.8m/s^2 regardless of mass
Not enough information

Answer 1

Answer:

No, because g=9.8m/s^2 regardless of mass

Step by step:

Since we have the height of the suspended rock, if we hav the mass, we can calculate the potential energy.

U = mass*gravity*height.

Since the potential energy is transformed into kinetic energy as the rock falls, we can use the relation of the kinetic energy

K =  0.5*mass*(velocity^2)

To find the speed with which the rock hits the ground.

Answer 2

Answer:

No, because g=9.8m/s^2 regardless of mass

Explanation:

As we know that the rock is suspended at a given height above the surface

so here the gravitational potential energy of the rock will convert into its kinetic energy

so here we will have

$\frac{1}{2}mv^2 = mgh$

$v^2 = 2gh$

$v = \sqrt{2gh}$

so the final speed does not depends on the mass of the object but the only thing that it depends is the height.

so here correct answer is given as

No, because g=9.8m/s^2 regardless of mass