2. An apple with a mass of 3 kg falls from a branch 2 meters high. Just before it hits the ground, it has a velocity of 6.26 m/s. What is the gravitational potential energy of the apple before it starts to fall?

Gravitation Potential energy is converted into the Kinetic Energy, when it just reaches the ground. Some amount of energy is wasted in sound and heat energy when it strikes the ground.

Explanation:

When the apple falls from the tree, it has some gravitational potential energy due to its height.  

Now, When it starts falling, the Gravitation Potential energy will starts converting into the Kinetic Energy.

When the apple is about to strikes the ground, the Gravitational Potential energy have been converted into the Kinetic Energy.

When it strikes the Ground, some amount of the energy is converted into heat and unsold energy and some amount of the energy is used in deforming the shape of the Apple.

Hope it helps.