Question

The p.e of mass m at height 50m above the ground is 100J. At what height from the ground its P. E becomes 200J?​

Answer 1

Explanation:

When answering these questions, keep in mind the law of Conservation of Energy.

We know that energy cannot be created nor destroyed - therefore it will still be 200J when it hits the ground

When GPE Increases = KE Decreases

When GPE Decreases = KE Increase

Draw a diagram of a ball falling and above that ball write GPE = 200J & KE = 0J (assuming its not in free fall at this point and we are holding it per say)

And beside that draw the same diagram but this time the ball touching the ground, GPE = 0J & KE = 200J.

Answer 2

Provided that:

• Height = 50 m
• Potential energy = 100 J

To determine:

• The height from the ground its P.E becomes 200 J?

Solution:

• At 100 m from the ground its P.E becomes 200 J.

Using concept:

• Potential energy formula

Using formula:

• P.E = mgh

Where, P.E denotes potential energy, m denotes mass, g denotes acceleration due to gravity and h denotes height.

Knowledge required:

• The universal value of g = 9.8 m/s sq. but we can take it as 10 m/s sq. as approx to solve questions to according to the situation!

Required solution:

~ Firstly let us find out the mass!

»»» P.E = mgh

»»» 100 = m × 10 × 50

»»» 100 = m × 500

»»» m = 100/500

»»» m = 1/5 kg

»»» m = 0.2 kg

»»» Mass = 0.2 kg

~ Now let us calculate the height from the ground its(mass) P.E becomes 200 J!

»»» P.E = mgh

»»» 200 = 0.2 × 10 × h

»»» 200 = 2 × h

»»» 200/2 = h

»»» 100 = h

»»» h = 100 m

»»» Height = 100 m $\:$