Olympiad – Class IX – Science - Phy - Force and Laws of Motion

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Question - 1

An unbalanced force acts on a body. What happens to the body?

  • A The body remains at rest.
  • B The body must move with uniform velocity.
  • C The body is accelerated.
  • D The body moves along a circle

Question - 2

If no force acts on a body, then what will happen to it?

  • A It does not change its shape.
  • B It continues to move but with less speed.
  • C It changes its direction.
  • D It can either remain at rest or continue to move in a straight line.

Question - 3

How much mass (approximately) of a body one can hold, when a force of 1N is applied on it?

  • A 100 mg
  • B 100 g
  • C 1kg
  • D 10kg

Question - 4

When a bus starts suddenly, the passengers are pushed backwards. Which of the following laws is illustrated in this example?

  • A Newton's first law
  • B Newton's second law
  • C Newton's third law
  • D None of Newton's law

Question - 5

A force of a given magnitude acts on a body. On what factors does the acceleration of the body depend?

  • A Density of the body
  • B Volume of the body
  • C Mass of the body
  • D Shape of the body

Question - 6

What does the principle of conservation of linear momentum state?

  • A The linear momentum of a system cannot be changed.
  • B The linear momentum of a system cannot remain constant.
  • C The linear momentum of a system can be changed only if internal forces act.
  • D The linear momentum of a system can be changed only if external forces acts on it.

Question - 7

On which of the following do actionreaction forces act upon?

  • A Same body
  • B Different bodies
  • C Along different lines
  • D In the same direction

Question - 8

Consider a porter standing on a platform with a suitcase which presses his head with a force of 200 N. If this force is taken to be the action, from where is the reaction force exerted and to where is it directed?

  • A The head, on the suitcase
  • B The earth, on the suitcase
  • C The earth, on the porter
  • D The suitcase, on the earth

Question - 9

A force produces an acceleration of 5.0 cm S-2 when it acts on a body of mass 20 g. Find the force acting on the body.

  • A 1 x 10-3 N
  • B 2 x 10-3 N
  • C  4 X 10-3 N
  • D 5 x 10-3 N

Question - 10

A force eas one body of mass 200. The velocity of the body changes from 15 m S-1 to 25 m S-1 in 2.5 s. What is magnitude of the force, assuming the force to be constant

  • A 0.4 N
  • B 0.5 N
  • C 0.6 N
  • D 0.8