Quick questions on Kinetic and potential energy explained: O-Level Physics

6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.

What is kinetic energy?

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Kinetic energy is the energy an object has because it is moving:

What is gravitational potential energy?

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Gravitational potential energy is the energy an object has because of its height above the ground:

What are notice the mass cancels?

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mgh = \tfrac{1}{2}mv^2

the mass appears on both sides and cancels, leaving

v = \sqrt{2gh}

. So, ignoring air resistance, the final speed of a dropped object depends only on the height, not on its mass, matching the free-fall result.

What is q1?

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4.0\ \text{kg}

object moves at

5.0\ \text{m s}^{-1}

. Calculate its kinetic energy. [2 marks]

What is q2?

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3.0\ \text{kg}

box is lifted

2.0\ \text{m}

(

g = 10\ \text{N kg}^{-1}

). Calculate its gain in gravitational potential energy. [2 marks]

What is q3?

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Explain, using energy, why a faster car needs a longer distance to stop. [2 marks]

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