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

Which of the following statements is/are false? a. There can be frictional force between two surfaces when there is no relative motion between the two. b. Higher the viscosity of fluid, greater will be the frictional force acting on an object moving through it. c. When objects move through fluids, they lose some of their energy in overcoming the fluid friction, decreasing their efficiency.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. None of the above
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option, as all the statements are true. 

Multiple choice

Most significant which imposes limitations in raising the high speeds is

  1. adhesion of wheels

  2. resistance due to oscillations

  3. flange resistance

  4. air or wind resistance
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Wheel-rail adhesion is the most significant limiting factor for high-speed trains. Without sufficient friction between steel wheels and steel rails, locomotives cannot transmit tractive effort effectively. This friction coefficient is typically only 0.15-0.35 on dry rail and drops further with moisture or contamination, making it the fundamental constraint on acceleration and speed.

Multiple choice

Creep is the..... movement of rails.

  1. longitudinal

  2. diagonal

  3. horizontal

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

Creep refers to the gradual longitudinal movement of rails in the direction of traffic. This occurs due to the impact of moving wheels, thermal expansion, and traction forces, causing rails to progressively shift over time.

Multiple choice

On curves, to counteract the effect of centrifugal force, the level of outer rail is raised above the inner rail by a certain amount. This is called

  1. track gradient

  2. track slope

  3. super elevation

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

Super elevation is the raising of the outer rail above the inner rail on curves to counteract centrifugal force, ensuring trains remain stable and comfortable. Track gradient (option A) refers to vertical slope, track slope (option B) is not a standard term, and horizontal gradient (option D) incorrectly combines gradient direction with super elevation.

Multiple choice

The apparent force that acts on all masses in a non-inertial frame of reference is

  1. Van der Waals forces

  2. London dispersion forces

  3. Entropic force

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

A fictitious force, also called a pseudo force is an apparent force that acts on all masses in a non-inertial frame of reference, such as a rotating reference frame. The force F does not arise from any physical interaction but rather from the acceleration a of the non-inertial reference frame itself.

Multiple choice

Work done by the potential energy of the object, which is above the ground is not ______________.

  1. directly proportional to the height from the ground

  2. directly proportional to the mass of the object

  3. inversely proportional to the height from the ground

  4. directly proportional to the gravitational force

  5. measured in joules
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is correct as W is directly proportional to the height not inversely proportional. W = mass x gravity x height.

Multiple choice

The force by which an object attracts other object is directly proportional to the product of their masses, is ___________________.

  1. the frictional force

  2. the gravitational force

  3. the magnetic force

  4. the thrust

  5. the pressure
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, it is the gravitational force. Every object in the universe attracts other object by a force of attraction, called gravitation, which is directly proportional to the product of masses of the objects and inversely proportional to the square of distance between them.

Multiple choice

When is the work done said to be positive?

  1. If the body is displaced in the same direction of force.

  2. If the body is displaced and returns to same point.

  3. If the body is displaced in the opposite direction of force.

  4. If the body is not displaced.

  5. If the body is displaced, irrespective of the direction of force.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Yes, if the body is displaced in the same direction of force, work done is positive.

Multiple choice

Which of the following is true about free fall?

  1. Object falls under the influence of gravity.

  2. Fall of parachute towards Earth.

  3. Free fall is independent of the mass of object falling.

  4. Option 1 and 2.

  5. Option 1 and 3.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Yes, it is correct as both 1 and 3 are true.

Multiple choice

A body will continue in a state of rest, or uniform motion in a _______, unless an external force acts on it.

  1. circular path

  2. straight line

  3. axis

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

Newton's first law of inertia states that an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced external force. The motion must be uniform (constant velocity) in a straight line.