CBSE Class 9 Science Force and Laws of Motion MCQs Set C

Question: A water tanker filled up to two-thirds of its tank with water is running with a uniform speed. When the brakes are suddenly applied, the water in its tank would :
a) move backward
b) move forward
c) rise upwards
d) remain unaffected
Answer: b

Question: If we release a magnet held in our hand, it falls to the ground. The force which makes the magnet fall down is an example of :
a) balanced force
b) unbalanced force
c) magnetic force
d) muscular force
Answer: b

Question: When a rubber balloon held between the hands is pressed, its shape changes. This happens because :
a) balanced forces act on the balloon
b) unbalanced forces act on the balloon
c) frictional forces act on the balloon
d) gravitational forces act on the balloon
Answer: a

Question: ‘When a hanging carpet is beaten with a stick, the dust particles start coming out of it’. This phenomenon
can be best explained by making use of :
a) Newton’s third law of motion
b) Newton’s law of gravitation
c) Newton’s first law of motion
d) Newton’s second law of motion
Answer: c

Question: When a toothpaste tube is squeezed, its shape changes. The force responsible for this is an example of :
a) balanced forces
b) centripetal forces
c) unbalanced forces
d) centrifugal forces
Answer: a

Question: Which of the following effect cannot be produced by an unbalanced force acting on a body ?
a) change in speed of the body
b) change in shape of the body
c) change in direction of motion of the body
d) change in state of rest of the body
Answer: b

Question: A passenger in a moving train tosses a coin which falls behind him. This shows that the motion of train is
a) accelerated
b) uniform
c) retarded
d) along circular track
Answer: a

Question: The inertia of a moving object depends on :
a) momentum of the object
b) speed of the object
c) mass of the object
d) shape of the object
Answer: c

Question: The inertia of an object tends to cause an object :
a) to increase its speed
b) to decrease its speed
c) to resist a change in its state of motion
d) to decelerate due to friction
Answer: c

Question: When we talk of a force acting on a body, it usually means :
a) electrical force
b) balanced force
c) unbalanced force
d) nuclear force
Answer: c

Question: Name the physical quantity whose unit is kg.m/s.
Answer: Momentum

Question: State whether momentum is scalar or vector.
Answer: Vector

Question: Name the property of bodies (or objects) to resist a change in their state of rest or of motion.
Answer: Inertia

Question: What is the other name of Newton’s first law of motion ?
Answer: Galileo’s law of inertia

Question: What name is given to the product of mass and velocity of a body ?
Answer: Momentum

Question: When a ball is dropped from a height, its speed increases gradually. Name the force which causes this change in speed.
Answer: Force of gravity

Question: State whether force is a scalar or a vector quantity.
Answer: Vector

Question: With which physical quantity should the speed of a running bull be multiplied so as to obtain its momentum ?
Answer: Mass (of bull)

Question: Name the unbalanced force which slows down a moving bicycle when we stop pedalling it.
Answer: Force of friction

Question: Name the physical quantity which is considered to be a measure of the quantity of motion of a body.
Answer: Momentum

Question: The mass of object A is 6 kg whereas that of another object B is 34 kg. Which of the two objects, A or B, has more inertia ?
Answer: b

Question: What is the total momentum of the bullet and the gun before firing ?
Answer: Zero

Question: What is the usual name of the forces which cannot produce motion in a body but only change its shape ?
Answer: balanced forces

Question: State whether the following statement is true or false :
Unbalanced forces acting on a body change its shape.
Answer: false

Fill in the following blanks with suitable words :

Question: ……………….. is a measure of the inertia of a body.
Answer: Mass

Question: Newton’s first law of motion is also called Galileo’s law of …………………
Answer: inertia

Question: When a stationary car starts suddenly, the passengers are jerked …………..
Answer: backward

Question: If there were no unbalanced force of …………… and no ………….. resistance, a moving bicycle would go on moving for ever.
Answer: friction ; air

Question: When a running car stops suddenly, the passengers are jerked …………
Answer: forward