Work Done by a Force at an Angle · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Work when the push is at an angle

Science · Energy · ages 16-18
Name ______________________   Date ____________

  1. A force at right angles to the motion does zero work.

    Circle one:   True   False

  2. In W equals F d cos theta, what is theta?

    • The distance moved
    • The mass of the object
    • The angle between force and displacement

  3. What is one joule?

    • One newton with no motion at all
    • One newton through one metre in its own direction
    • One kilogram falling for one second

  4. You pull a sledge with a rope at 30 degrees to the ground. Which part of the pull does work?

    • Only the along-ground part
    • Only the upward part
    • Both parts equally

  5. A 20 N force pushes an object 5 m while tilted 60 degrees from the motion. Cos 60 is 0.5. Give the work in joules.

    Answer: ______________

  6. A generator lowers a briefcase at steady speed. What is the sign of the work it does on the case?

    • Zero, since the speed is steady
    • Negative, since force and motion oppose each other
    • Positive, since the case moves down

  7. A rope pulls a sledge with 100 N at 60 degrees to the ground. Cos 60 is 0.5. The sledge moves 6 m. Give the work of the pull in joules.

    Answer: ______________

  8. Two identical crates slide the same distance. One is pushed along the motion, the other with the same force at 60 degrees. Which push does more work?

    • The along-motion push
    • The angled push
    • Both do the same
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Work when the push is at an angle W1-mt_OvBtur6dW5-s1

  1. True · Cos 90 is zero, so the whole product is zero.
  2. The angle between force and displacement · Theta measures how far the push tilts away from the motion.
  3. One newton through one metre in its own direction · Work units are force times distance: the newton metre.
  4. Only the along-ground part · Only the component along the displacement counts.
  5. 50 · Multiply 20 by 5 by 0.5 to get 50 J.
  6. Negative, since force and motion oppose each other · Upward force against downward motion gives negative work.
  7. 300 · Only the along-ground part works: 100 times 0.5 times 6 is 300.
  8. The along-motion push · Tilting wastes part of the force, since cos 60 is only 0.5.
Worksheet · LightMySky