Potential Energy MCQs Quiz | Class 9

Class IX Science (086), Unit III: Motion, Force and Work. This quiz focuses on Potential Energy, covering its meaning, formula (P.E. = mgh), and dependence on position and height. Attempt these 10 MCQs to test your grasp of the topic, then submit to check your score and download the answer key PDF.

Understanding Potential Energy

Potential Energy (P.E.) is the energy possessed by an object by virtue of its position or configuration. It is often referred to as stored energy. The most common form discussed in Class 9 is Gravitational Potential Energy.

Key Concepts

  • Definition: The energy present in a body due to its position above the ground or a change in its shape/size.
  • Formula: For an object of mass m raised to a height h against gravity (acceleration due to gravity g), the energy is given by: Ep = mgh.
  • Work Done: The work done to lift an object against gravity is stored in the object as potential energy.
  • SI Unit: Like all forms of energy, the SI unit is the Joule (J).

Factors Affecting Potential Energy

From the formula mgh, we can see that Potential Energy depends directly on:

  1. Mass (m): Heavier objects have more potential energy at the same height.
  2. Height (h): The higher an object is lifted, the greater its potential energy.
  3. Gravity (g): It depends on the gravitational pull of the planet (constant near Earth’s surface).

Path Independence

The work done by gravity depends only on the initial and final vertical positions, not on the path taken. Whether you lift a stone straight up or carry it up a ramp to the same height, the change in potential energy is the same.

Feature Gravitational P.E. Elastic P.E.
Cause Height above ground Change in shape (stretch/compress)
Example Water in a dam, stone on a roof Stretched bow, compressed spring

Quick Revision Points

  • Potential Energy is a scalar quantity.
  • At the ground level, height is usually taken as zero, so P.E. is zero.
  • Energy can transform from Potential to Kinetic (e.g., dropping a ball).

Extra Practice Questions

  1. A 10 kg bag is lifted 2 meters. Calculate P.E. (g=9.8 m/s2). [Ans: 196 J]
  2. Does a stretched rubber band possess energy? Yes, Elastic Potential Energy.
  3. If height is tripled, how does P.E. change? It becomes three times.
  4. Is work done against gravity positive or negative when lifting? Work done by lifting force is positive; work done by gravity is negative.
  5. Define 1 Joule of P.E. (Energy of 1N weight at 1m height).