Forces MCQ Quiz - Objective Question with Answer for Forces - Download Free PDF

The correct answer is F/16.

Given that, 

m1 = m1/4,

m2 = m2/4,

keeping d = constant.

As F α (m1 × m2 ) /r2

Then the new Force is 

Fnew = G (m1/4) × (m2/4)/r2  = F/16

The correct option is F/16.

​Key Points

• Gravitational force: It states that the force of attraction between any two bodies is directly proportional to the product of their masses and is inversely proportional to the square of the distance between them.
  • ​It can also be defined as the universal force of attraction, which is acting between objects, is known as the gravitational force.​
  • F = Gm1m2/r2
  • where F = gravitational force between two bodies, m1 = mass of the first body, m2 = mass of the second body, r = distance between the centres of two bodies.

The Correct answer is Zero.

Key Points

• Balanced forces are equal in magnitude and opposite in direction.
• When balanced forces act on an object, they cancel each other out.
• This results in no net force acting on the object.
• As a result, the object remains in its current state of motion, either staying at rest or continuing to move with a constant velocity.
• According to Newton's First Law of Motion, an object will remain at rest or in uniform motion unless acted upon by an unbalanced force.
• Therefore, when balanced forces are applied, the net force is zero, and there is no change in the object's motion.

 Additional Information

• Equal to the mass of the object
  • The mass of an object is a measure of the amount of matter it contains and is not related to the net force acting on the object.
  • Mass remains constant regardless of the forces applied to the object.
• Equal to acceleration
  • The net force acting on an object is equal to the mass of the object multiplied by its acceleration (F = ma), according to Newton's Second Law of Motion.
  • This option is incorrect because it does not consider the condition of balanced forces, which result in zero net force and no acceleration.
• Infinite
  • An infinite force is an unrealistic and impractical concept in physics.
  • Balanced forces do not imply an infinite force but rather equal and opposite forces that cancel each other out.

The Correct answer is Gravitational force.

Key Points

• Gravitational force is a type of non-contact force, meaning it acts even when there is no physical contact between objects.
• This force is responsible for the attraction between two masses, such as between the Earth and objects on its surface.
• The strength of the gravitational force depends on the mass of the objects and the distance between them, as described by Newton's Law of Gravitation.
• It plays a significant role in governing the motion of celestial bodies, such as planets, stars, and moons.
• Gravitational force is what keeps us anchored to the Earth's surface and is also responsible for phenomena like ocean tides, caused by the gravitational pull of the Moon and the Sun.
• This force is a fundamental aspect of classical physics and has applications in fields such as astrophysics, space exploration, and engineering.

Additional Information

• Muscular force
  • Muscular force is a type of contact force that occurs due to the action of muscles in living organisms.
  • It is used for performing tasks like pushing, pulling, lifting, and walking.
  • This force is exerted when there is a physical interaction between objects.
• Frictional force
  • Frictional force arises when two surfaces are in contact and resist motion relative to each other.
  • It acts in the opposite direction to the motion and is crucial for activities like walking, driving, and holding objects.
  • Friction is a contact force and depends on the nature of the surfaces and the force pressing them together.
• Tension force
  • Tension force is a contact force transmitted through a string, rope, or cable when it is pulled tight by forces acting at its ends.
  • This force is crucial in structures like bridges, elevators, and cranes.

The Correct answer is Zero.

Key Points

• Balanced forces are equal in magnitude and opposite in direction.
• When balanced forces act on an object, they cancel each other out.
• This results in no net force acting on the object.
• As a result, the object remains in its current state of motion, either staying at rest or continuing to move with a constant velocity.
• According to Newton's First Law of Motion, an object will remain at rest or in uniform motion unless acted upon by an unbalanced force.
• Therefore, when balanced forces are applied, the net force is zero, and there is no change in the object's motion.

 Additional Information

• Equal to the mass of the object
  • The mass of an object is a measure of the amount of matter it contains and is not related to the net force acting on the object.
  • Mass remains constant regardless of the forces applied to the object.
• Equal to acceleration
  • The net force acting on an object is equal to the mass of the object multiplied by its acceleration (F = ma), according to Newton's Second Law of Motion.
  • This option is incorrect because it does not consider the condition of balanced forces, which result in zero net force and no acceleration.
• Infinite
  • An infinite force is an unrealistic and impractical concept in physics.
  • Balanced forces do not imply an infinite force but rather equal and opposite forces that cancel each other out.

The correct answer is Zero.

Key Points

• Balanced forces occur when the net force acting on an object is zero, meaning the forces acting on the object are equal in magnitude and opposite in direction.
• When forces are balanced, the object remains in its current state of motion—either at rest or moving with constant velocity—as per Newton’s First Law of Motion.
• Balanced forces result in no acceleration of the object, as net force is directly proportional to acceleration (F = ma).
• Examples of balanced forces include a book resting on a table where the gravitational force is counteracted by the normal force of the table.
• In the context of balanced forces, the term “net force” is defined as the vector sum of all forces acting on an object, which equals zero in this case.

Additional Information

• Newton’s First Law of Motion: Also known as the law of inertia, it states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
• Net Force: The overall force acting on an object when all the individual forces are combined. If the forces cancel out, the net force is zero.
• Unbalanced Forces: When the forces acting on an object do not cancel out, resulting in a nonzero net force that causes the object to accelerate.
• Force Measurement: Force is measured in Newtons (N), named after Sir Isaac Newton, and is calculated using the formula F = ma (Force = mass × acceleration).
• Equilibrium Condition: An object is said to be in mechanical equilibrium when the sum of all forces and torques acting on it is zero, leading to no change in its motion.

The correct option is Thrust Force.

Key Points

• Thrust is the force that moves an aircraft through the air.
• Thrust is used to overcome the drag of an airplane, and to overcome the weight of a rocket.

Additional Information 

• Drag Force: The air resistance that tends to slow the forward movement of an airplane. 
• Gravity Force: The force that pulls all objects towards the earth. 
• Lift Force: The upward force that is created by the movement of air above and below a wing. Air flows faster above the wing and slower below the wing, creating a difference in pressure that tends to keep an airplane flying.

CONCEPT:

• Work-energy theorem: It states that the sum of work done by all the forces acting on a body is equal to the change in the kinetic energy of the body i.e.,

Work done by all the forces = Kf - Ki

\(W = \frac{1}{2}m{v^2} - \frac{1}{2}m{u^2} = {\bf{Δ }}K\)

Where v = final velocity, u = initial velocity and m = mass of the body

EXPLANATION:

Given that:

• Mass of the Object (m) = 1 kg
• Initial velocity of the object (u) = 4m/s
• Final velocity of the object (v) = 8m/s
• Total net work is done W _(net) = Kinetic energy (During final velocity) – Kinetic Energy (During Initial Velocity).
• Now by substituting the values in the above equation, we get

W_(net) = ½ mv² – ½ mu²

= ½ (1)×(8)² – ½ (1)×(4)²

= 32 - 8 Joule

= 24 Joules.

• Therefore, the total work done by the force is 24 J.

The correct answer is ​Tension force.

Key Points

• A car towing another car with a chain is an example of a Tension force.
• The force of tension is defined as the force which is transmitted by rope, string, or wire when pulled by forces acting from opposite sides.
• The force of stress is directed over the length of the wire and at the ends pulls energy evenly on the bodies.
• Any physical object that is in contact with each other exerts some force.
• Cables and ropes can be used to exert forces since they can easily move a force over a given distance (e.g. the length of the rope). 

Additional Information

• Frictional Force refers to the force produced by two surfaces that come in contact and slide against each other.
• An applied force is a force that a human or some other object applies to an entity. If an individual moves a desk across the room, then an applied force acts on the object.
• The Normal force is the force of support exerted on an object which is in contact with another stable object. It always occurs perpendicular to the surface.

CONCEPT:

• Work: Work is said to be done by a force when the body is displaced actually through some distance in the direction of the applied force.
• Since the body is being displaced in the direction of F, therefore work done by the force in displacing the body through a distance s is given by:

\(W = \vec F \cdot \vec s\)

• Thus work done by a force is equal to the scalar or dot product of the force and the displacement of the body.

EXPLANATION:

Given that:

Mass (m) = 25 kg.

Distance (s) = 15 m.

Work (W) = 480 J.

Using equation:

\(Work = Force × Distance\)

∴ 480 = F × 15

F = \(480\over15\)= \(32\ N\)

Force = 32 N.

The correct answer is F/16.

Given that, 

m1 = m1/4,

m2 = m2/4,

keeping d = constant.

As F α (m1 × m2 ) /r2

Then the new Force is 

Fnew = G (m1/4) × (m2/4)/r2  = F/16

The correct option is F/16.

​Key Points

• Gravitational force: It states that the force of attraction between any two bodies is directly proportional to the product of their masses and is inversely proportional to the square of the distance between them.
  • ​It can also be defined as the universal force of attraction, which is acting between objects, is known as the gravitational force.​
  • F = Gm1m2/r2
  • where F = gravitational force between two bodies, m1 = mass of the first body, m2 = mass of the second body, r = distance between the centres of two bodies.

We have been given

a = –10 m/s²; t = 3 s and v = 0 m/s.

v = u + at 

0 = u + (–10 m/s²) × 3s

u = 30 m/s

s = u t + 1/2 a t²

= 30 × 3 + 1/2 × -10 × 3 × 3

= 90 - 45

= 45 m

• This constant tug on the Moon as it moves around the Earth is called a "centripetal" force. This force is balanced by the "centrifugal" force, that pulls on the Earth and keeps the moon in motion.
• The moon revolves around earth because of Earth’s gravitational force.
• The Gravitational force of Earth tends to attract Moon.
• The centripetal force acts on a body, moving in a circular path, and is directed towards the center around which the body is moving.

→ Given data -

• Mass, m = 40 kg

Height, h = 5m

Time, t = 4s

• Work done, W = mgh

W = 40 × 10 × 5 [g = 10 m/s², given]

W = 2000 joules

→ Power, P = work done /time

P = 2000/4

P = 500 joule/sec

The correct answer is 3 ms^-1 and 4500 N.

Key Points

The initial velocity of the truck, u =0 ms^-1

The time taken by car, t = 30 s

Distance covered by the car, s = 1350 m

According to second law of motion,

s = ut + 1/2 (at²)

Put the values,

1350 = 0 x 30 + 1/2 (a x 900)

1350 = 450a

a = 3 ms-2

Now, Force = mass x acceleration

Force = 1500 x 3 = 4500 N

The correct answer is option 2 i.e. Gravitational force.

• All objects in the universe attract each other. This force of attraction between objects is called the gravitational force.
• The attractive or repulsive forces between particles or objects due to their electric charges is known as electrostatic force.
• The force resulting due to the action of muscles is known as the muscular force; since it can be applied only when it is in contact with an object, it is also called a contact force.
• The force of attraction or repulsion that arises between electrically charged particles because of their motion is known as a magnetic force.