Class 8 Interactive Science Lesson

Work, Energy and the Work Energy Relation

Read the illustrated story, revise the main concepts, complete the assessment and explore higher order thinking questions.

Learning Goals

Use these goals to understand what students should know and demonstrate after the lesson.

Use the text buttons or numbered page buttons to move through the story.

Cover Page, page 1 of 11

Think about each question before revealing the suggested answer.

1. A student pushes a wall, but the wall does not move. Is work done on the wall?

No. The work done on the wall is zero because the displacement is zero.

2. Why does water become warm in Joule's experiment?

The mechanical work done by the falling weights is converted into heat energy, which raises the temperature of the water.

3. How does Joule's experiment support the law of conservation of energy?

It demonstrates that mechanical energy changes into heat energy. Energy changes form, but it is not lost.

Review the most important ideas from the lesson.

What is work in science?

Work is done when a force causes an object to move through a distance in the direction of the force.

What is the SI unit of work and energy?

The SI unit of both work and energy is the joule, represented by the symbol J.

What happens when force does not produce displacement?

The work done is zero because displacement is required for mechanical work to occur.

What did Joule's experiment demonstrate?

Joule's experiment demonstrated that mechanical work can be converted into heat and supported the principle of conservation of energy.