Physics · Science General

Newtonian Mechanics and Forces

1,559 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 physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

A ball moving on a table top eventually stops. What is the reason ?

  1. due to gravity.

  2. due to friction between the ball and table

  3. due to other external force.

  4. none of these.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Due to the force of friction between the ball and table top, it  opposes the motion of the ball. And, gradually its speed keeps on decreasing and the ball finally stops.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

Object will remain at rest or in uniform motion in a straight line unless acted upon by an external force - which law is this ?

  1. Newton's third law

  2. Newton's first law

  3. Newton's second law

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

Statement of Newton's first law of motion,

It states that a body will remain at rest or in state of motion unless an external force is applied to the object.
To have any changes in state of object , force is necessary.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

The acceleration produced in a body by a force of given magnitude depends on:

  1. size of the body

  2. shape of the body

  3. mass of the body

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Newton's second law of motion, $F=ma$, where $m$ is mass of an object which acquires acceleration $a$ when force $F$ is applied on it.
For a force of constant magnitude, $a\propto{\dfrac{1}{m}}$ i.e. acceleration is inversely proportional to mass.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

An object moving at constant velocity must:

  1. have a net force on it

  2. eventually stop due to gravity

  3. not have any force of gravity on it

  4. have zero net force on it
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The object moving with constant velocity must have zero acceleration i.e. $a _{net} = 0$. From Newton's IInd law the net external force must be zero in case of zero acceleration.

Net external force acting on the object  $F _{net} = ma _{net} = 0$
Hence answer D is correct.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

Every body continues to be in its state of rest or of non-uniform motion in a straight line unless compelled by some external force to act otherwise. This is stated by:

  1. Newton's 1st law

  2. Newton's 2nd law

  3. Newton's 3rd law

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

The premise of question is external force is zero and conclusion is  state of motion of body will be at rest or non uniform motion. However, the non uniform motion is only applicable in case of external force being applied to body, hence the statement is false.

So, given statement is stated by none of Newton's laws.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

If there are many forces acting on an object, it must have a non-zero net (unbalanced) force acting on it.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In case of many forces acting on the body, it can be in equilibrium,which implies zero external force. For example in case of ladder supported by a wall there are frictional and gravitational forces working at wall and floor, which balances each other so that ladder does not move. Hence the given statement is false.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

Consider a ball at rest in the middle of a toy wagon. When the wagon is pulled forward, the ball:

  1. Rolls forward

  2. Stays stationary

  3. Rolls sidewards

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

The relative motion between ball and toy wagon is zero before being pulled. As the wagon is pulled, the inertia of ball causes ball to maintain its state of rest, so the ball rolls backwards when wagon is moved in forward direction.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

It is advised to tie any luggage kept on the roof of a bus with a rope because of :

  1. Newtons first law

  2. Newtons second law

  3. Newtons third law

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

Luggage kept on the roof of a bus has the tendency to maintain its state of rest when bus is in rest and to maintain the state of motion when bus is in motion according to Newtons First Law of Motion. When bus will come in motion from its state of rest, in order to maintain the position of rest, luggage kept over its roof may fall down(backward). Similarly, when a moving bus will come in the state of rest or there is any sudden change in velocity because of applying of brake, luggage may fall down(forward) because of its tendency to remain in the state of motion.
This is the cause that it is advised to tie any luggage kept on the roof a bus with a rope so that luggage can be prevented from falling down.