CBSE Class 9 Physics Force And Laws Of Motion Worksheet Set A

Read and download free pdf of CBSE Class 9 Physics Force And Laws Of Motion Worksheet Set A. Students and teachers of Class 9 Physics can get free printable Worksheets for Class 9 Physics in PDF format prepared as per the latest syllabus and examination pattern in your schools. Standard 9 students should practice questions and answers given here for Physics in Grade 9 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 9 Physics Worksheets prepared by school teachers as per the latest NCERT, CBSE, KVS books and syllabus issued this academic year and solve important problems provided here with solutions on daily basis to get more score in school exams and tests

Force And Laws Of Motion Class 9 Physics Worksheet Pdf

Class 9 Physics students should refer to the following printable worksheet in Pdf for Force And Laws Of Motion in standard 9. This test paper with questions and answers for Grade 9 Physics will be very useful for exams and help you to score good marks

Class 9 Physics Worksheet for Force And Laws Of Motion

 

CBSE Class 9 Physics Worksheet - Force and Laws of Motion

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 Exam Questions NCERT Class 9 Science Chapter 9 Force and Laws of Motion

FORCE AND LAWS OF MOTION

Question. What is Newton's First Law known as? The Law of
A. Friction.
B. Mass.
C. Inertia.
D. Gravity
Ans : Inertia


Question. Motions need an unbalanced net force to maintain
A. True.
B. False
Ans : true


Question. Which has more Inertia? (so need more force to move)
A. Truck.
B. Ant.
C.A cat.
D.A skateboard
Ans : Truck


Question. What is Newton's First Law
A. F=ma
B. Every action has an equal and opposite reaction
C. An object at rest stays at rest, an object in motion stays in motion.
D. Friction
Ans : An object at rest stays at rest, an object in motion stays in motion.


Question. friction is a force that acts
A. in the same direction as the motion
B. opposite to the direction of the motion
C. opposite to the applied forces
D. the same direction as the applied force
Ans : opposite to the direction of the motion


Question. What is the name for a push or pull?
A. A movement.
B. A force.
C. Speed.
D. Density
Ans : B


Question. What can a force do?
A. start a motion
B. stop a motion
C. change the direction of the motion
D. All of the above
Ans : all of the above


Question.Which type of force(s) will cause a change in an object's motion?
A. Gravity.
B. zero net force.
C. balanced forces.
D. unbalanced forces
Ans : Unbalanced force


Question. What kind(s) of objects have inertia?
A. all objects with mass.
B. only objects at rest.
C. only objects in motion.
D. only objects whose motion is being changed
Ans : All objects with mass


Question. Which one needs a greater net force to move, a kilogram of feathers or a kilogram of iron?
A. feathers
B. iron.
C. same.
D. depends on their friction
Ans : Depends on their friction


Question. an object with a zero net force could be moving
A. true.
B. false
Ans : False


Question. an object with a zero net force could be moving in a circle at a constant speed
A. false.
B. true
Ans : True


Question. Which object has more inertia — a Bowling ball or a tennis ball?
Ans : 
A bowling ball


Question. The passenger in a running bus tends to lean forward , when the bus stops suddenly. This is due to
A. inertia of motion.
B. Inertia in rest
C. Inertia with direction
D. None of the above
Ans : Inertia if motion


Question. The moment the ball was thrown, the ball was also in motion alone with the person who has thrown the ball. This is the example of :-
A. Newton’s second law of motion
B. Newton’s mass law of motion
C. Newton’s first law of motion
D. All of the above
Ans : Newton’s first law of motion.


Question. Why are tyres corrugated and made rough?
Ans : Tyres are corrugated and made rough to increase friction.
(1) This provides better grip on the road.
(2) It also prevents the vehicles from slipping.


Question. Why you get hurt by hitting a stone while when you kick a football it flies away?
Ans : This is because stone is heavier than football and heavier objects offer larger inertia. When we kick a football its mass is less and inertia is also less so force applied by our kick acts on it and hence it shows larger displacement but in case of stone, it has more mass and offers larger inertia. When we kick (action) the stone it exerts an equal and opposite force (reaction) and hence it hurts the foot.


Question. State the law of conservation of momentum.
Ans : (i) Momentum of two bodies before collision is equal to the momentum after collision.
(ii) In an isolated system, the total momentum remains conserved.


Question. Why is it dangerous to jump out from a moving bus?
Ans : While moving in a bus our body is in motion. On jumping out of a moving bus our feet touches the ground and come to rest. While the upper part of our body fall in motion and moves forward due to inertia of motion and hence we can fall in forward direction.
Thus, to avoid this we need to run forward in the direction of bus.


Question. When we hold a bag full of books in our hand steady at some height above the ground, what kind of forces are acting on it?
Ans : The bag full of books is steady. This means its position is fixed. So, it must be under balanced forces. The forces acting on it are :
(i) Weight (or the gravitational pull) downwards,
(ii) Upward force applied by the person holding the bag.


Question. Why all cars are provided with seat belts?
Ans : Sudden movement of the vehicle results in the sudden change in the state of motion of the vehicle when our feet are in contact with it. But the rest of our body opposes this change due to its inertia and tends to remain where it was. Seat belts are provided to protect the passengers from falling backward or forward during such situation.


Question. Why are athletes made to fall either on a cushioned bed or on a sand bed in a high jump athletic event?
Ans : In a high jump athletic event, athletes are made to fall either on a cushioned bed or on a sand bed so as to increase the time of the athlete’s fall to stop after making the jump. This decreases the rate of change of momentum and hence the force.


Question. Which concept is behind the phenomenon- “A boatman pushes the river bank with a bamboo pole to take his boat into the river”.
Ans : When the boatman pushes the river bank with a bamboo pole, the river bank offers an equal and opposite reaction. This reaction helps the boat to move into the river.


Question. Why does a fireman struggle to hold a hose-pipe?
Ans : A fireman has to make a great effort to hold a hosepipe to throw a stream of water on fire to extinguish it. This is because the stream of water rushing through the hose-pipe in the forward direction with a large speed exerts a large force on the hose-pipe in the backward direction.


Question. What happens when a quick jerk is given to a smooth thick cardboard placed on a tumbler with a small coin placed on the cardboard? The coin will fall in the tumbler. Why?
Ans : The coin was initially at rest. When the cardboard moves because of the jerk, the coin tends to remain at rest due to inertia of rest. When the cardboard leaves contact with the coin, the coin falls in the tumbler on account of gravity.


Question. Why is it necessary to bend knees while jumping from greater height?
Ans :
(i) Our feet come to rest at once during the jump.
(ii) Due to the less time a large force acts on the feet.
(iii) If we bend out knees, the time of impact increases. Hence, less force acts on the feet.


Question. Why is it difficult to achieve a zero unbalanced force in practical situations? In practice what happens to a rolling marble? How can we reduce the effect of friction on a marble?
Ans :
(i) It is difficult to achieve a zero unbalanced force because of the presence of the frictional force acting opposite to the direction of motion.
(ii) In practice, the rolling marble stops after travelling some distance.
(iii) The effect of frictional force may be reduced by using a smoother marble and a smoother plane and providing a lubricant.

 

More Question..

Multiple Choice Questions

1. Which of the following statement is not correct for an object moving along a straight path in an accelerated motion?
(a) Its speed keeps changing
(b) Its velocity always changes
(c) It always goes away from the earth
(d) A force is always acting on it

2. The forces of action and reaction are
(a) always equal only
(b) always equal and opposite
(c) always equal but in same direction
(d) always unequal and opposite.

3. According to the third law of motion, action and reaction
(a) always act on the same body
(b) always act on different bodies in opposite directions
(c) have same magnitude and directions
(d) act on either body at normal to each other

4. The action and reaction forces at
(a) on different bodies always
(b) on some body always
(c) on same body, sometimes
(d) on different bodies, sometimes

5. A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goal keeper to
(a) exert larger force on the ball
(b) reduce the force exerted by the ball on hands
(c) increase the rate of change of momentum
(d) decrease the rate of change of momentum

6. The inertia of an object tends to cause the object
(a) to increase its speed
(b) to decrease its speed
(c) to resist any change in its state of motion
(d) to decelerate due to friction

7. Principle of conservation of linear momentum is deduced from
(a) Newton’s first law
(b) Newton’s second law
(c) Newton’s third law
(d) none of the above

8. The function of mud guards is based on
(a) inertia of rest
(b) inertia of direction

 


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