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NSC / Matric Work and Energy — practice questions

Explore 28 free Work and Energy questions in NSC / Matric Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Work and Energy questions and exercises with answers

Showing questions 1–28 of 28.

In physics, when is work done on an object by a force?Read the answer and worked solution →A force acts at right angles to the direction in which an object is moving. How much work does that force do?Read the answer and worked solution →A competitor carries two very heavy sleds across level ground at a steady height. How much work does he do on the sleds?Read the answer and worked solution →The net force on an object does work on that object. What must change as a result?Read the answer and worked solution →What is the defining feature of a conservative force?Read the answer and worked solution →Complete the work-energy theoremRead the answer and worked solution →True or false: conservative forcesRead the answer and worked solution →Conservative or not?Read the answer and worked solution →Reading the theoremRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →Two are true, one is notRead the answer and worked solution →Tap every test for a conservative forceRead the answer and worked solution →Order the reasoning: from work to speedRead the answer and worked solution →Flip and pair: term with meaningRead the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →True or false: energy bookkeepingRead the answer and worked solution →Speeds up, slows down, or neither?Read the answer and worked solution →Applying the work-energy theoremRead the answer and worked solution →True or false: potential energyRead the answer and worked solution →Kinetic or potential?Read the answer and worked solution →Tap every statement true of a closed pathRead the answer and worked solution →Spot the one that does not belongRead the answer and worked solution →Assertion and reason: energyRead the answer and worked solution →Complete the potential energy relationRead the answer and worked solution →Flip and pair: quantity with what it tracksRead the answer and worked solution →Two are true, one is notRead the answer and worked solution →Order the reasoning: why a pendulum keeps swingingRead the answer and worked solution →Conservative or not, in practiceRead the answer and worked solution →

Worked practice questions

In physics, when is work done on an object by a force?

  1. When it acts across the motion
  2. When it acts along the motion
  3. Whenever the object has mass
  4. Whenever the object is heavy
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Correct answer: B. When it acts along the motion

1. Work is the process of transferring energy by means of a force. 2. That transfer needs the object to move while the force acts on it. 3. It also needs part of the force to lie along the line of that movement. 4. So work is done when the force acts in, or against, the direction of the motion. _Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 5: Work, energy and power_

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A force acts at right angles to the direction in which an object is moving. How much work does that force do?

  1. All of it
  2. Half of it
  3. None at all
  4. Twice as much
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Correct answer: C. None at all

1. Only the part of a force that lies along the motion can transfer energy to the object. 2. A force at right angles to the motion has no part lying along that direction. 3. So a perpendicular force does no work at all, however large it is. 4. This is why the normal force on a sliding block does no work on it. _Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 5: Work, energy and power_

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A competitor carries two very heavy sleds across level ground at a steady height. How much work does he do on the sleds?

  1. A lot of work
  2. Negative work
  3. Half the work
  4. No work at all
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Correct answer: D. No work at all

1. Everyday language would call carrying heavy sleds very hard work. 2. In physics the test is whether the force has a part along the displacement. 3. His force on the sleds points straight up to balance gravity, while the sleds move sideways. 4. There is no part of his force along the displacement, so he does no work on the sleds. 5. His muscles do use energy to keep the force going, but that energy is not transferred to the sleds, so the answer is not a lot of work. _Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 5: Work, energy and power_

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