Sample QuestionsForce and Laws of Motion questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
A cup of water holding a steel ball $(m)$ is allowed all under gravity. The reaction between the ball and the base of the cup is:
- A
$\text{mg}$
- B
$2\text{mg}$
- C
$\frac{\text{Mg}}{2}$
- ✓
$\text{zero}$
Answer: D.
View full solution →Fill in the blanks:
A push or a pull on an object are types of $.......?$
Answer: D.
View full solution →Amphibians of the plant kingdom are the:
Answer: D.
View full solution →The process of walking involves:
- A
Newton's first law of motion
- B
Newton's second law of motion
- ✓
Newton's third law of motion
- D
Answer: C.
View full solution →You are on a frictionless horizontal plane. You can get off the plane:
- A
- ✓
By throwing some pieces of stone
- C
By rolling your body on the surface
- D
Answer: B.
View full solution →In the following Questions, the Assertion and Reason have be put forward. Read the statements careful and choose the correct alternative from the following:
Assertion: You are hurt more when you fall on cushion than on hard floor.
Reason: Momentum change occurs over a shorter time interval on hitting a hard surface than on a soft cushion.
- A
Both the Assertion and the Reason a correct and the Reason is the correct explanation of the Assertion.
- B
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
- C
Assertion is true but the Reason is false.
- ✓
Both Assertion and Reason are False.
Answer: D.
View full solution →In the following Questions, the Assertion and Reason have be put forward. Read the statements careful and choose the correct alternative from the following:
Assertion: The ratio of the $S.I.$ to $C.G.S.$ unit of forces is $10^5.$
Reason: Water evolving out of a hose exerts no force on the pipe.
- A
Both the Assertion and the Reason a correct and the Reason is the correct explanation of the Assertion.
- ✓
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
- C
Assertion is true but the Reason is false.
- D
The statement of the Assertion is false but the Reason is true.
Answer: B.
View full solution →In the following Questions, the Assertion and Reason have be put forward. Read the statements careful and choose the correct alternative from the following:
Assertion: Atheletes fall on a cushion in a high jump event to avoid getting hurt.
Reason: Time to come to rest is increased to reduce the force.
- A
Both the Assertion and the Reason a correct and the Reason is the correct explanation of the Assertion.
- ✓
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
- C
Assertion is true but the Reason is false.
- D
The statement of the Assertion is false but the Reason is true.
Answer: B.
View full solution →In the following Questions, the Assertion and Reason have be put forward. Read the statements careful and choose the correct alternative from the following:
Assertion: We should always wear a seat belt while travelling in a car.
Reason: Seat belt prevents us from falling forward due to inertia when sudden breakes are applied.
- ✓
Both the Assertion and the Reason a correct and the Reason is the correct explanation of the Assertion.
- B
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
- C
Assertion is true but the Reason is false.
- D
The statement of the Assertion is false but the Reason is true.
Answer: A.
View full solution →In the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as: Assertion: Rocket moves on the principle of conservation of energy.
Reason: Conservation of momentum is not applicable for motion of rocket.
- A
If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
- B
If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
- C
If Assertion is true, but Reason is false.
- ✓
If Assertion and Reason both are false.
Answer: D.
View full solution →Greater the mass less is the inertia of motion but greater is the inertia of rest. [True/ False]
A body cannot have zero velocity but non zero momentum together. [True/ False]
The gun recoils on firing a bullet due to reaction force exerted by bullet. [True/ False]
When a rolling football stops on its own, it violates the first law of motion. [True/ False]
Impulse is equal to change in momentum. [True/ False]
Fill in the following blanks with suitable words: _________ is a measure of the inertia of a body.
Leaves get detached from a tree due to ________.
Fireman holds a hose by exerting a _________.
Fill in the following blanks with suitable words: Newton’s first law of motion is also called Galileo’s law of ________.
Impulse has the $S.I.$ unit of ________.
View full solution →The time taken to stop a ball rolling with velocity u is reduced to half, find the change in values of: Initial and final momenta.
State whether force is a scalar or a vector quantity.
State the relation between the momentum of a body and the force acting on it.
Explain, why is it difficult for a fireman to hold a hose, which ejects large amounts of water at a high velocity.
Name the physical quantity whose unit is ‘newton’.
Two persons manage to push a motorcar of mass $1200$ kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of $0.2 m s ^{-2}$. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort.)
View full solution →An object of mass $1 kg$ travelling in a straight line with a velocity of $10 m s ^{-1}$ collides with, and sticks to, a stationary wooden block of mass $5 kg$ . Then they both move off together in the same straight line. Calculate the total momentum just before the impact and just after the impact. Also, calculate the velocity of the combined object.
View full solution →A bus starts from the stop and take $50s$ to get the speed of $10m/s$. If the mass of the bus along with passengers is $10000kg,$ then calculate the force applied by the engine of bus to push the bus at the speed of $10m/s.$
View full solution →A large truck and a car, both moving with a velocity of magnitude $u,$ have a head on collision and both of them come to a half after that. If the collision lasts for. Which vehicle experiences the greater change in momentum$?$
View full solution →A horse continues to apply a force in order to move the cart with a constant speed. Explain why?
What is the momentum in kgm/s of a $10\ kg$ car travelling at $(a) 5\ m/s$ $(b) 20\ cm/s$, and $(c) 36\ km/h?$
View full solution →If a balloon filled with air and its mouth untied, is released with its mouth in the downward direction, it moves upwards. Why?
A body at rest opposes the force which tries to move it. Name this property and give two examples to illustrate it.
Two identical bullets are fired one by a light rifle and another by a heavy rifle with the same force. Which rifle will hurt the shoulder more and why?
A $1000kg$ vehicle moving with a speed of $20m/s$ is brought to rest in a distance of $50$ metres:
- Find the acceleration.
- Calculate the unbalanced force acting on the vehicle.
View full solution →A ball $X$ of mass $1\ kg$ travelling at $2\ m/s$ has a head-on collision with an identical ball $Y$ at rest. $X$ stops and $Y$ moves off. Calculate the velocity of $Y$ after the collision.
View full solution →How long will it take a force of 1$0$ N to stop a mass of $2.5$ kg which is moving at $20 m / s$ ?
View full solution →State and prove the law of conservation of linear momentum.
A boy of mass $50\ kg$ running at 5m/s jumps on to a $20\ kg$ trolley travelling in the same direction at $1.5\ m/s$. What is their common velocity?
View full solution →Derive the unit of force using the second law of motion. A force of $5\ N$ produces an acceleration of $8 m\mathrm{s}^{-2}$ on a mass $\mathrm{m}_1$ and an acceleration of $24 \mathrm{~m} \mathrm{~s}^{-2}$ on a mass $\mathrm{m}_2$. What acceleration would the same force provide if both the masses are tied together$?$
View full solution →The sum of momentum of the two objects before collision is equal to the sum of momentum after the collision provided there is no external unbalanced force acting on them. This is known as the law of conservation of momentum. This statement can alternatively be given as the total momentum of the two objects is unchanged or conserved by the collision. Law of conservation of momentum is applicable to system of particle. Answer the following questions.
(i)Law of conservation of momentum is applicable to
$(a)$ A system of particles
$(b)$ Only for $2$ particles
$(c)$ Only for $1$ particle
$(d)$ None of the above
(ii) Law of conservation of momentum holds good provided that
$(a)$ There should be external unbalanced force acting on particles
$(b)$ There should not be any external unbalanced force acting on particles
$(c)$ No internal forces acting on particles
$(d)$ None of the above
(iii)The total momentum of the two objects when collision occurs is
$(a)$ Changed
$(b)$ Remains conserved
$(c)$ Become zero
$(d)$ None of the above
(iv) State law of conservation of momentum.
(v) If action and Reaction are equal in magnitude and opposite in direction then why they do not cancel each other?
View full solution →The third law of motion states that when one object exerts a force on another object, the second object instantaneously exerts a force back on the first. These two forces are always equal in magnitude but opposite in direction. These forces act on different objects and neveron the same object. It is important to note that even though the action and reaction forces are always equal in magnitude; these forces may not produce accelerations of equal magnitudes, this is because each force acts on a different object that may have a different mass.The two opposing forces are also known as action and reaction forces. Answer the following questions.
(i) Action reaction forces are always
$(a)$ Equal and in same direction
$(b)$ Equal and in opposite direction
$(c)$ Unequal and in same direction
$(d)$ None of the above
(ii) Which of the following is correct about action reaction forces?
$(a)$ They act on different objects
$(b)$ They are equal in magnitude and opposite in direction
$(c)$ Both forces acted on different object simultaneously
$(d)$ All the above
(iii) State third law of motion
(iv) Give 5 examples of third law of motion
(v) Even though the action and reaction forces are always equal in magnitude; these forces may not produce accelerations of equal magnitudes. Give your justification on this statement
View full solution →The second law of motion is quantitative expression of force and it states that the rate of change of momentum of an object isproportional to the applied unbalanced force in the direction of force. Mathematically, $F$ = ma, the unit of force is $kg-m/s^2$ or Newton,which has the symbol $N$. The second law ofmotion gives us a method to measure the force acting on an object as a product of its mass and acceleration.Answer the following questions.
(i) SI unit of force is
$(a)$ Newton
$(b)$ $Kg-m/s^2$
$(c)$ Both $a$ and $b$
$(d)$ None of the above
(ii) The quantitative expression of force is given by
$(a)$ First law of motion
$(b)$ Second law of motion
$(c)$ Third law of motion
$(d)$ None of the above
(iii) Force is directly proportional to
$(a)$ Acceleration of object
$(b)$ Time for which force acts on object
$(c)$ Both a and b
$(d)$ None of the above
(iv) State second law of motion. State whether it is scalar or vector quantity
(v) Differentiate between first law and second law of motion.(give 3 points)
View full solution →Two strings $X$ and $Y$ are tied to the two opposite faces of the block as shown in figure. If we apply a force by pulling the string $X$, the block begins to move to the right. Similarly, if we pull the string$ Y$, the block moves to the left. But, if the block is pulled from both the sides with equal forces, the block will not move. Such forces are called balanced forces and do not change the state of rest or of motion of an object. Now, let us consider a situation in which two opposite forces of different magnitudes pull the block. In this case, the block would begin to move in the direction ofthe greater force. Thus, the two forces are not balanced and the unbalanced force acts in the direction the block moves. This suggests that an unbalanced force acting on an object brings it in motion. Force is push or pull.
$(i)$ Force is nothing but
$(a)$push
$(b)$pull
$(c)$both push or pulls
$(d)$none of the above
$(ii)$ When balanced forces acting on moving object then
$(a)$ Object continue to move with same speed
$(b)$ Object will change its direction of motion
$(c)$ Object will come to rest
$(d)$ None of the above
$(iii)$ When unbalanced force acts on moving object opposite to direction of motion then
$(a)$ Object continue to move with same speed
$(b)$ Object will come to rest
$(c)$ Both can be possible
$(d)$ None of the above
(iv) Differentiate between balanced and unbalanced force. give 3 points each .
(v) From above diagram if one person pull from Y rope with 10N force and another person pull from X rope with 5N force. In which direction box will move? Is this a case of unbalanced force or balance force?
View full solution →Newton’s first law of motion states that a body at rest will remain at rest position only and a body which is in motion continues to be in motion unless otherwise they are acted upon by an external force. In other words, all objects resist a changein their state of motion. In a qualitative way, the tendency of undisturbed objects to stayat rest or to keep moving with the same velocity is called inertia. This is why, the firstlaw of motion is also known as the law of inertia. Answer the following questions.
(i) The first law of motion is also known as
$(a)$law of inertia/p>
$(b)$law of thermodynamics
$(c)$both $a$ and $b$
$(d)$none of these
(ii) If no external force acts on object which is at rest. it will
$(a)$remain at rest
$(b)$start to move
$(c)$both a and b can possible
$(d)$none of these
(iii) If no external force acts on moving object. it will
$(a)$stop moving
$(b)$continue to move with same speed in same direction
$(c)$changes its direction of motion
$(d)$none of these
(iv) State Newton’s first law of motion.
(v) why Newton’s first law of motion is called law of inertia
View full solution →