CBSE Questions for Class 9 Physics Force And Laws Of Motion Quiz 13 - MCQExams.com

A block rests on the floor. Two forces act, one is downward gravitational force and second one is upward reaction force by the floor. These two forces:
  • have equal magnitudes and the same direction
  • have equal magnitudes but opposite directions
  • have unequal magnitudes and the same direction
  • have unequal magnitudes and opposite directions
  • None of these
A 60 kg man pushes a 40 kg man with a force of 60 N. With what force does the 40 kg man push the other man?
  • 40 N
  • 0 N
  • 60 N
  • 20 N
Which of the following effects cannot be produced by a force?
  • Changing the mass of an object
  • Changing the shape of an object
  • Changing the position of an object
  • Changing the direction of movement of an object
When a running horse suddenly stops, the rider falls  _________.
  • forwards
  • backwards
  • to his right
  • to the horse's right
A fish is swimming in the ocean. Which of the following represents the interaction between the fish and the water?
  • The force of the fish points back while the force of the water points forward
  • The force of the fish must be greater than the force of the water for the fish to move
  • The force of the fish must be less than the force of the water for the fish to move
  • The forces point in the same direction in liquid media such as the ocean
  • Newton's third law does not apply in water
There are two forces of equal magnitude acting on the ball. Choose the correct option which show ball has constant velocity.
State whether true or false.
Newton's first law of motion gives the concept of momentum.
  • True
  • False
At the Earth, a block of mass $$m$$ which rest on the frictionless table,  let $$F$$ be the force required to produce acceleration $$a$$. Calculate the force at the Moon to produce same acceleration if  $$g_{moon}$$ is one sixth of $$g_{earth}$$.
  • $$\dfrac{F}{12}$$
  • $$\dfrac{F}{6}$$
  • $$\dfrac{F}{3}$$
  • $$F$$
  • $$6F$$
A lead block is suspended from your hand by a string. The reaction due to the force of gravity on the block is the force exerted by
  • the string on the block
  • the block on the string
  • the string on the hand
  • the gravitational force acting on earth due to block
The rubber band is stretched by the weight of the mass suspended on it, but it is not moving. The action force that causes the rubber band to stretch comes from the earth. Identify the reaction force of the force pair?
  • The rubber band pulling on the mass
  • The rubber band pulling on the earth
  • The mass pulling on the rubber band
  • The mass pulling on the earth
  • The earth pulling on the rubber band
While dusting a carpet, we give it a sudden jerk or beat it with a stick because: 
  • the inertia of rest keeps the dust in its position and the dust is removed when the carpet moves away.
  • the inertia of motion removes dust.
  • no inertia involved in process.
  • jerk compensates for the force of adhesion between dust and carpet and dust is removed.
State whether true or false.
A tennis ball and an iron ball are thrown towards us with the same velocity. Then, the tennis ball is harder to catch as compared to an iron ball.
  • True
  • False
If a body is acted upon by a constant force then it will have a uniform _________.
  • velocity
  • acceleration
  • inertia
  • momentum
If KE of a given particle is doubled, its momentum will be:
  • Doubled
  • Tripled
  • Increases by $$\sqrt{2}$$ times
  • Remains unchanged
Momentum is a measure of quantity of _______.
  • motion
  • friction
  • gravitation
  • electric force
Inertia means resistance to the change of state.
  • True
  • False
State whether true or false.
Even when the net force acting on a body is zero, the body may move with constant acceleration.
  • True
  • False
Select the correct options.
  • Action and reaction never act on the same body. If it were so, the total force on a body would have always been zero, i.e., the body will always remain in equilibrium.
  • A book lying on a table exerts a force on the table which is equal to the weight of the book. This is the force of action.
  • The table supports the book, by exerting an equal force on the book. This is the force of reaction.
  • None of these
A body is at rest on the surface of the earth. Which of the following statements is correct?
  • No force is acting on the body
  • Only weight of the body acts on it
  • Net downward force is equal to the net upward force
  • None of the above statement is correct
From Newton's third law,  Action and reaction____.
Which of the following will not fit in the above sentence.
  • acts on the same body
  • are equal
  • are opposite in direction
  • acts on different bodies
On which one of the following conservation laws, does a rocket work?
  • Mass
  • Energy
  • Linear momentum
  • Angular momentum
What force is required to produce an acceleration of $$3 {m}/{{s}^{2}}$$ in an object of mass $$0.7 kg$$?
  • 2.1
  • 100
  • 1.1
  • 5
In accordance with Newton's third law of motion 
  • Action and reaction forces balance each other
  • For appearance of action and reaction, physical contact is not necessary
  • This law is applicable whether the bodies are at rest or they are in motion
  • All of these
Three charges $$4q, Q$$ and q are in a straight line in the position of $$0, 1/2$$ and I respectively. The resultant force on q will be zero, if Q=
  • - q
  • $$-2q$$
  • $$-\frac{q}{2}$$
  • $$4q$$
A Gardner waters the plants by a pipe of diameter $$1\ mm$$. The water comes out at the rate or $$10\ cm^{3}/sec$$. The reaction force exerted on the hand of the Gardner is:
  • $$0$$ N
  • $$1.27\times 10^{-2}N$$
  • $$1.27\times 10^{-4}N$$
  • $$0.127\ N$$
A rocket of mass 1000 kg is to be projected vertically upwards. The gases are exhausted vertically downwards with velocity $$100\, ms ^{-1}$$ with respect to the rocket. What is the minimum rate of burning of fuel, so as to just lift the rocket upwards against, the gravitational attraction? (Take $$g= 10\, ms^{-2} $$) :
  • $$50\, kgs^{-1}$$
  • $$100\, kgs^{-1}$$
  • $$200\, kgs^{-1}$$
  • $$400\, kgs^{-1}$$
A ship of mass $$3 \times 10^7$$ kg, initially at rest, is pulled by a force of $$5 \times 10^4 N$$ through a distance of 3 m. Assuming that the resistance due to water is negligible, the speed of the ship is
  • $$1.5 m/s$$
  • $$60 m/s$$
  • $$0.1 m/s$$
  • $$5 m/s$$
A rider on horse falls back when horse starts running all of a sudden because
  • Rider is taken back
  • Rider is suddenly afraid of falling
  • Inertia of rest keeps the upper part of body at rest while lower part of the body moves forward with the horse.
  • Inertia of motion keeps the upper part of body at rest while lower part of the body moves forward with the horse.
A small child tries to move a large rubber toy placed on the ground. The toy does not move but gets deformed under her pushing force $$\left( { F }  \right) $$ which is obliquely upward as shown. Then
632847_4613e49adb1a40e8a46be93fac504ceb.png
  • The resultant of the pushing force $$\left( { F } \right) $$, weight of the toy, normal force by the ground on the toy and the frictional force is zero
  • The normal force by the ground is equal and opposite to the weight of the toy
  • The pushing force $$\left( { F } \right) $$ of the child is balanced by the equal and opposite frictional force
  • The pushing force $$\left( { F } \right) $$ of the child is balanced by the total internal force in the toy generated due to deformation
"To every action, there is equal and opposite reaction". It is Newton's
  • First Law
  • Second Law
  • Third Law of Motion
  • None of these
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