Energy is the first topic that majority of the students would study in Primary 6. Similar to other topics, there are certain misconceptions that are extremely common among students. The following question is an example of one common misconception in the topic of Energy.

Before I discuss in detail about this misconception, let me bring you through the fundamentals of Energy.

**The 8 Types of Energy**

**Energy is needed to do work and students are required to know 8 types of Energy, which are:**

- Gravitational Potential Energy
- Chemical Potential Energy
- Elastic Potential Energy
- Kinetic Energy
- Light Energy
- Heat Energy
- Electrical Energy
- Sound Energy

Students have learnt Heat Energy and Light Energy in Primary 4 and Electrical Energy (Electricity) in Primary 5. Thus, the focus of Primary 6 would be on Potential Energy and Kinetic Energy. In today’s post, I will be discussing one form of Potential Energy (i.e Gravitational Potential Energy).

**Gravitational Potential Energy (GPE)**

Gravitational Potential Energy (GPE) is energy an object possesses due to its position in a gravitational field.

The amount of gravitational potential energy an object possesses depends on two factors:

**1. Mass of the object**

The greater the mass of the object, the greater the amount of gravitational potential energy possessed by the object.

**2. Height of the object from the ground**

The greater the height of the object from the ground, the greater the amount of gravitational potential energy possessed by the object.

With the above knowledge, let us now look at the following question.

**Here’s The Question**

*Rosyth School/2014/P6/SA1/Q42*

In this question, John loaded a box onto a lorry by pushing it up a ramp from the ground to the back of the lorry.

By changing the length of the ramp used, part b of the question serves to test students on their understanding of the factors affecting gravitational potential energy of the box, which are

**1. Mass of the object**

The greater the mass of the object, the greater the amount of gravitational potential energy possessed by the object.

**2. Height of the object from the ground**

The greater the height of the object from the ground, the greater the amount of gravitational potential energy possessed by the object.

**The Thought Process**

As the mass of the box remained the same, most students would be able to identify that this question is testing on how the height of the box above the ground affects gravitational potential energy.

However, some students tend to mistake the height of the box from the ground as the length of the ramp.

Thus, some students will answer this question incorrectly by stating that the amount of gravitational potential energy of the box at Point B is different when the length of the ramp is changed.

When we mention ‘*height of the box from the ground*’, we are looking at the **perpendicular/ vertical height of the box from the ground**, as seen by the red arrow.

*Illustrating Height From The Ground*

As such, regardless the length of the ramp, the perpendicular/ vertical height of the box from the ground **remains the same** and **would not affect the gravitational potential energy of the box.**

Thus, the answer would be:

The amount of potential energy of the box at Point B would be the same as the height of the box from the ground and the mass of the box remains the same.

**Once again…**

Hope this helps!

If you’d like your child to enhance his/her thought processes & answering techniques, I welcome your child to join us in our upcoming Complete Concept Integration™ Science workshop!

To learn more about the **Primary 5** CCI™ Science workshop, please click **here!**

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