Physics · Science General

Newtonian Mechanics and Forces

1,605 Questions

Newtonian mechanics studies the motion of objects and the physical laws governing them. This hub covers friction, gravitational force, inertia, and vector quantities. Mastering these fundamental physics concepts is essential for various government competitive exams.

Laws of motionFriction and inertiaVector and scalar quantitiesGravitational accelerationArchimedes principle

Newtonian Mechanics and Forces Questions

Multiple choice

What does the Newton’s third law states?

  1. The rate of change of momentum is equal to the force applied

  2. For every reaction there is an opposite reaction

  3. The body is rest until a force is applied

  4. The body is tend to be rotated if the force is applied tangentially
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The requirement of the third law is important in the equilibrium of the body. Specially the rigid bodies. The rigid body particles are in the equilibrium and are thus facing the forces and to be in the equilibrium they also react and apply the opposite force and thus the third law of newton.

Multiple choice

Which of the following statements is false about forces/couple?

  1. Moment of couple is free vector

  2. Resultant and equilibrant are equal in magnitude and direction

  3. Resultant of a couple is always zero

  4. Parallelogram law is to be proved experimentally
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Resultant and equilibrant are equal in magnitude and direction

Multiple choice

The ratio of static friction to dynamic friction is always

  1. Greater than one

  2. Less than one

  3. Equal to one

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Static friction is the force required to initiate motion, which is always greater than the dynamic (kinetic) friction required to maintain motion once it has started.

Multiple choice

The ratio of static friction to dynamic friction is always

  1. Greater than one

  2. Equal to one

  3. Less than one

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Static friction is the force required to initiate motion, which is always greater than the dynamic (kinetic) friction required to maintain motion once it has started.

Multiple choice physics wave motion reflection of waves

Reflection at a free boundary implies

  1. restoring force is zero

  2. restoring force is not zero

  3. applied force is zero

  4. applied force is not zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a free boundary, the restoring force is always zero

The correct option is (a)

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

Streamlining of the rocket :

  1. minimizes the friction of air.

  2. maximizes the friction of air.

  3. Either A or B is correct depending on the weight of the rocket.

  4. Both A and B.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Whenever any object moves through air, air opposes the motion. This is known as air resistance. 

The intensity of air resistance depends on the area of the surface which is perpendicular to the direction of motion.
To reduce this resistance, the face of the rocket is made almost conical. This is known as streamlining. 
Streamlining minimizes air resistance and increases the speed of the rocket. 

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

Blow a balloon and let it go. You will find it moving in the direction opposite to the direction in which the air is ejected. This demonstrates :

  1. the principle of rocket propulsion

  2. the principle of combustion

  3. the principle of conservation of energy

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The principle of rocket propulsion works on the 'Newton's Third Law of Motion'. It states that, 'to every action, there is always an equal and opposite reaction'.

In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.
This is how a rocket is propelled.
Rocket propulsion is similar to the example of the situation in which, if we blow a balloon and let it go, it starts moving in the direction opposite to the direction in which the air is ejected. 
Balloon forces out the air inside it. The air applies an equal and opposite reaction force to the balloon.

Multiple choice chemistry in daily life satellite launch vehicles rocket propellants

The propulsion of a rocket is based on the principle of conservation of

  1. linear momentum

  2. energy

  3. angular momentum

  4. mass
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The rocket propulsion is based on the principle of linear momentum conservation as initially the rocket is at rest but when the rocket is ready to take off the the momentum of small mass of gas ejected at high speed is compensated by increased momentum of the rocket with the remaining fuel.

Multiple choice physics satellite launch vehicles rocket propellants universe and space science xx radio telescope and space telescopes launching vehicles

The principle of rocket propulsion depends on :

  1. Newton's third law of motion

  2. Principle of conservation of momentum

  3. Either A and B

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The principle of rocket propulsion works on the 'Newton's Third Law of Motion'. It states that, 'to every action, there is always an equal and opposite reaction'.

In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.
This is how a rocket is propelled.
The principle of conservation of momentum states that whenever two bodies collide or get separated, then their  total momentum before collision or separation is equal to their total momentum after collision or separation.
Since the gases of the rocket and the rocket are stationery at the start, their total momentum is zero. After the gases start burning, the momentum imparted to the rocket is equal and opposite to that of the gases. Hence their total momentum is zero.

Multiple choice physics free, damped and forced oscillations damped harmonic motion damped oscillation free, forced and damped oscillations

The periodic vibrations of a body of decreasing amplitude in the presence of resistive force on it are called

  1. Forced vibrations

  2. Free vibration

  3. Damped vibrations

  4. All
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Forced vibrations: External force is acting on the body. 
Free vibration: Constant amplitude and no external force.
Damped vibration: Amplitude is not constant, it keeps on decreasing due to environmental factors of the system like air resistance.  
Therefore, correct option is C. 

Multiple choice physics hooke's law

Change in the shape of a body caused by the application of a force (stress) is called as :

  1. ductility

  2. deformation

  3. hardness

  4. rigidity
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If a force on a body changes the normal positions of the molecules of a body, resulting in a change in the configuration of the body, then the force applied is called deforming force and change in shape of the body is called deformation. 

Multiple choice physics hooke's law

Change in shape of a body caused by the application of stress is called:

  1. rigidity

  2. elasticity

  3. sheer

  4. deformation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Deformation of a body is the change in shape of a body caused by the application of stress. According to the Hooke's law, the deformation caused in an elastic material is directly proportional to the stress applied to it.