Potential Energy Formula | Problems (With Answers)

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Potential Energy Formula

Potential energy (PE) is the product of mass (m), gravitational acceleration (g) and the height (h). Using the formula of potential energy: PE = m g h, the value of potential energy of an object can be calculated.

Let’s solve some problems based on this formula, so you’ll get a clear idea.

Potential Energy Practice Problems

Problem 1: Calculate the potential energy of a 1.5 kg book which is about to fall from the top of a 2.65 m bookshelf. (Take the value of gravitational acceleration, g = 9.8 m/s2)

Solution:

Given data:
Mass of a book, m = 1.5 kg
Height of a book, h = 2.65 m
Potential energy of a book, PE = ?
Gravitational acceleration, g = 9.81 m/s2

Using the formula of potential energy,
PE = m g h
PE = 1.5 × 9.81 × 2.65
PE = 38.99 J

Therefore, a book has the potential energy of 38.99 J, before it falls from the top of a bookshelf.

Problem 2: A stone of mass 4 kg, resting at the edge of the hill having a height of 50 m is about to fall. Calculate the potential energy of a stone right before it falls off the hill. (Take the value of gravitational acceleration, g = 9.8 m/s2)

Solution:

Given data:
Mass of a stone, m = 4 kg
Height of a stone, h = 50 m
Potential energy of a stone, PE = ?
Gravitational acceleration, g = 9.81 m/s2

Using the formula of potential energy,
PE = m g h
PE = 4 × 9.81 × 50
PE = 1962 J

Therefore, a stone has the potential energy of 1962 J, right before it falls off the hill.

Problem 3: What is the potential energy of a 500 gm fruit hanging from a tree branch that is about to fall from the height of 2 m? (Take the value of gravitational acceleration, g = 9.8 m/s2)

Solution:

Given data:
Potential energy of a fruit, PE = ?
Mass of a fruit, m = 500 gm = 0.5 kg
Height of a fruit, h = 2 m
Gravitational acceleration, g = 9.81 m/s2

Using the formula of potential energy,
PE = m g h
PE = 0.5 × 9.81 × 2
PE = 9.81 J

Therefore, a fruit hanging from a tree branch has the potential energy of 9.81 J.

Problem 4: One monkey of mass 10 kg sitting on the edge of a wall is about to jump from the height of 4 m. Calculate the potential energy of a monkey. (Take the value of gravitational acceleration, g = 9.8 m/s2)

Solution:

Given data:
Mass of a monkey, m = 10 kg
Height of a monkey, h = 4 m
Potential energy of a monkey, PE = ?
Gravitational acceleration, g = 9.81 m/s2

Using the formula of potential energy,
PE = m g h
PE = 10 × 9.81 × 4
PE = 392.4 J

Therefore, a monkey sitting on the edge of a wall has the potential energy of 392.4 J.

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