Question

17.
A 40 kg block is resting at a height of 5 m off the ground. If the block is released and
the ground, what is its total energy at a height of 2m?
(a) OJ (b) 400 S
C)2j (d) 6J (e) None

Answer 1

Answer:

A 40 kg block is resting at a height of 5 m off the ground. If the block is released and falls to the ground, what is its total energy at a height of 2m (g=10m/s2)?

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Energy stored at the highest point (i.e. at 5m) = mgh = 40Kg*9.8 m/second square*5m = 1960 J which is total energy of the object as well.

When the block was at height of 2m potential energy is decreased. At height of 2m potential energy = 40Kg*9.8 m/second square* 2 m= 784J and remaining energy may be kinetic or may be another form of energy.

According to Conservation of energy,

Total energy at highest point = Total energy at the lowest point

This suggests that total energy at height 2m is also 1960J.

Answer 2

Answer:

option (c) is correct answer

Explanation:

According to conservation of energy, energy will be same throughout the path.

So energy at highest point = mgh + 1/2 mv^2.

Here v = 0. (Body is resting).

Therefore, E = mgh = 40 * 10 * 5= 2000 Joules or 2 Kilo Joules.

This is also the energy at a height of 2m from the ground.