Class 9 Science Physics Force and laws of motion Very short Questions | Force & laws of motion MCQs/Short question | Force and laws of motion one shot questions
Q 1. Name the scientist who proved for the first time that objects move with constant speed when no force acts on them.
Answer. Galileo.
Q 2. Why do bicycles begin to slow down when we stop pedaling?
Answer. This is because of the frictional forces acting opposite to the direction of motion
Q 3. Which law of motion gives the measure of force?
Answer. Newton's second law of motion.
Q 4. Write the C.G.S unit of force.
Answer. Dyne.
Q 5. Can every force produce motion in every object?
Answer. No.
Q 6. When a force is applied to a body, what are the two essential effect it can produce?
Answer.
(a) It can bring about the change in the state of motion of a body or
(b) It can deform a body, i.e., it can change its shape.
Q 7. Define 1 newton force.
Ans. 1 newton is the magnitude of force which produces an acceleration of I m/s²
in a body of mass 1 kg.
Q 8. What do you mean by an impact force?
Answer. The force produced by the impact of a fast moving object on another is called
impact force.
Q 9. Define force of friction.
Answer. The force acting between any two surfaces in contact and tending to oppose
motion is called force of friction.
Q 10. Define electrostatic force.
Answer. The force exerted by an electrically charged body is called electrostatic force.
Q 11. If the body is found to be accelerated, is the force acting on it balanced or unbalanced?
Answer. Unbalanced.
Q 12. What do balanced forces usually do to a body?
Answer. Balanced forces usually produce a change in the shape of the body.
Q 13. When a body moves on flat surface, will its speed change?
Answer. No.
Q 14. What did Galileo conclude on the basis of his experiments on the motion of
objects?
Answer. A body continues to move with the same velocity if no unbalanced force acts on it.
Q 15. What do you mean by a resultant force?
Answer. When two or more forces act on a body simultaneously, then the single force
which produces the same effect as produced by all the forces acting together is known
as the resultant force.
Q 16. Do action and reaction act on the same body?
Answer. No, action and reaction act on different bodies.
Q 18. Write the SI unit of impulse.
Ans. Ns.
Q 19. What is the total momentum of a bullet and a gun before firing?
Answer. Zero.
Q 20. Name the principle on which a rocket works.
Answer. Newton's third law of motion
Q 21. Body A is heavier than body Q. Which has more inertia?
Answer. A has more inertia.
Q 22. A body is moving with uniform acceleration. Is its momentum constant?
Answer. No.
Q 23. Name the physical quantity that corresponds to the rate of change of momentum.
Answer. Force
Q 24. Which principle is involved in the working of a jet plane?
Answer. Newton's third law of motion.
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