Question

A stone of mass 4.5Kg is dropped from a building. At the top of the building at rest, its energy is 2500J. calculate the height of the building

Answer 1

Answer :

›»› The height of the building is 55.55 m.

Explanation :

Given :

• Mass of a stone = 4.5 kg.
• Top of the building at rest, it's energy = 2500 J.

To Find :

• Height of the building = ?

Formula required :

Here we use the formula to calculate the potential energy.

Formula of potential energy to calculate the height of the building is given by,

→ PE = mgh.

Here,

• PE is the Potential energy.
• m is the Mass of stone.
• h is the Acceleration due to gravity.
• h is the Heightof building.

Units,

• The unit of Potential energy is Joules (J).
• The unit of Mass is kilogram (kg).
• The unit of Acceleration due to gravity is meter per second square (m/s²).
• The unit of Height is meter (m).

We know that the value of acceleration due to gravity is 10 m/s².

Solution :

As we are given with the potential energy, mass of stone and acceleration due to gravity then we have the required formula, that is,

→ PE = mgh.

By using the formula of potential energy to calculate the height of the building and substituting all the given values in the formula, we get :

→ 2500 = 4.5 × 10 × h

→ 2500 = 45/10 × 10 × h

→ 2500 = 45 × 1 × h

→ 2500 = 45 × h

→ 2500 = 45h

→ h = 2500/45

→ h = 55.55

Hence, the height of the building is 55.55 m.

Answer 2

Answer:

Given:-

mass of stone =4.5kg

It's energy at the top of the building=2500J

To find:-

the height of the building

Solution:-

m=4.5kg

PE=2500J

• Height=h

we know that

$\boxed{\sf PE=mgh}$

• Substitute the values

$\longrightarrow\sf 2500=4.5×10×h$

$\longrightarrow\sf 2500=45h$

$\longrightarrow\sf h=\dfrac{2500}{45}$

$\longrightarrow\sf h=55.55$

$\therefore$ Height of the building is 55.55m.