Question

A 20-kilogram object strikes the ground with 1960 J of kinetic energy after falling freely from rest. How far above the ground was the object when it was released? *

Answer 1

Using the principle of conservation of mechanical energy, we calculate the height from which a 20-kilogram object was released to be 10 meters, given it had 1960 J of kinetic energy when striking the ground.

Step-by-step explanation:

To find how far above the ground a 20-kilogram object was when released, we can use the conservation of mechanical energy. The formula for gravitational potential energy is PE = m × g × h, and the object's kinetic energy (KE) when it strikes the ground is given as 1960 J. Since the object fell from rest, its initial KE is 0, so all of its mechanical energy was in the form of potential energy. Therefore, to calculate the height h from which it fell, we set the potential energy equal to the final kinetic energy:

PE = KE

m × g × h = 1960 J

20 kg × 9.8 m/s2 × h = 1960 J

h = 1960 J / (20 kg × 9.8 m/s2)

h = 10 m

Thus, the object was released from a height of 10 meters above the ground.

Answer 2

h = 10 m

Step-by-step explanation:

Given that,

Mass of an object, m = 20 kg

It strikes the ground with 1960 J of kinetic energy after falling freely from rest.

We need to find how far above the ground was the object when it was released. Let it is h.

The kinetic energy is converted to potential energy. It can be given by the relation as follows :

`E=mgh\\\\h=(E)/(mg)\\\\h=(1960)/(20* 9.8)\\\\h=10\ m`

So, it was at a height of 10 m when it was released.