Tag: force and newton's laws of motion

Questions Related to force and newton's laws of motion

An object moving at constant velocity must:

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

  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

Show answer
Correct Option: D
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.

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:

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

  1. Newton's 1st law

  2. Newton's 2nd law

  3. Newton's 3rd law

  4. None of the above

Show answer
Correct Option: D
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.

If no net force acts on an object, then the velocity of the object:

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

  1. remains same

  2. becomes zero

  3. increases

  4. decreases

Show answer
Correct Option: A
Explanation:

Newton's first law indicates that if no net force acts on an object, then the velocity of the object remains unchanged.

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

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

  1. True

  2. False

Show answer
Correct Option: B
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.

A ball is moving over a horizontal smooth surface with a constant velocity. Sum of external forces is:

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

  1. zero

  2. positive

  3. negative

  4. unity

Show answer
Correct Option: A
Explanation:

The ball is moving with a constant velocity, this implies the sum of external forces is zero

State whether given statement is True or False.
Is it possible to move in a curved path in the absence of a force?

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Any curve path can be assumed as summation if small circular arcs  of different radii. For a path to move at circular arc, there must be some force to provide it centripetal force to remain it in circular path. It is not possible to have motion along curved path without any force.

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

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

  1. Rolls forward

  2. Stays stationary

  3. Rolls sidewards

  4. Rolls backwards

Show answer
Correct Option: D
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.

State whether given statement is True or False.
You fall in the forward direction when a moving bus applies brakes to stop, and fall backward when it accelerates from rest.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

In a moving bus, passengers are in motion along with bus. When brakesare applied to stop a moving bus, bus comes in the position of rest. But because of tendency to be in the motion a person falls in forward direction.Similarly, when a bus is accelerated from rest, the tendency to be in rest, a person in the bus falls backwards.

Change in the state of rest or of uniform motion is brought about by:

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

  1. Acceleration

  2. Force

  3. Energy

  4. None

Show answer
Correct Option: B
Explanation:

Whenever an external force acts on a body there is a change in motion of the body. 

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

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

  1. Newtons first law

  2. Newtons second law

  3. Newtons third law

  4. None of these

Show answer
Correct Option: A
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.