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Class 8 Science — Forces: contact and non-contact

Sort forces by whether they need the objects to touch, read a spring balance, and keep weight and mass apart.

Name: ________________________

  1. 1.A ball is thrown straight up. Starting from The object moves straight up, put what happens next back into order.

    • Its speed goes on decreasing
    • The object moves straight up
    • It stops momentarily at the top
    • It falls back down, its speed increasing

  2. 2.What is the SI unit of force called? Give the one word.

  3. 3.Gravitational force differs from magnetic and electrostatic force in one important way. Which?

    • a) It acts on magnetic materials, while the other two act on any material
    • b) It has no unit, while the other two are measured in newtons
    • c) It acts without contact, while the other two need contact
    • d) It attracts and does not repel, while the other two can do either

  4. 4.Sort these forces by whether the two objects have to be touching for the force to act.

    Groups: Contact force · Non-contact force

    • Muscular force
    • Friction
    • Gravitational force
    • Magnetic force
    • Electrostatic force

  5. 5.A spring balance measures up to 10 N, with a bigger mark at each newton. Which mark is at 6 N?

    Mark the line with an X.

    012345678910

  6. 6.An object is carried to the Moon. Which of these changes, and which stays put?

    • a) Its weight changes; its mass stays the same
    • b) Neither changes
    • c) Its mass changes; its weight stays the same
    • d) Both change

  7. 7.An object placed in a liquid floats rather than sinks. What does the chapter say about the two forces on it?

    • a) The buoyant force acts downwards and the gravitational force upwards
    • b) The gravitational force is greater than the buoyant force
    • c) There is no gravitational force acting on a floating object
    • d) The buoyant force and the gravitational force are equal

  8. 8.The smallest division on a spring balance reads 0.5 N, and there are 2 divisions between the bigger marks. How far apart are the bigger marks, in newtons? Answer with a number.

Answer key — Class 8 Science — Forces: contact and non-contact

  1. 1. 1. The object moves straight up 2. Its speed goes on decreasing 3. It stops momentarily at the top 4. It falls back down, its speed increasing
  2. 2. newton
  3. 3. d) It attracts and does not repel, while the other two can do either
  4. 4. Muscular force → Contact force; Friction → Contact force; Magnetic force → Non-contact force; Electrostatic force → Non-contact force; Gravitational force → Non-contact force
  5. 5. 6
  6. 6. a) Its weight changes; its mass stays the same
  7. 7. d) The buoyant force and the gravitational force are equal
  8. 8. 1