Tag: force and newton's laws of motion

Questions Related to force and newton's laws of motion

The law that gives a qualitative definition of force 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. Newton's second law of motion

  2. Law of inertia

  3. Newton's third law of motion

  4. Law of gravitation

Show answer
Correct Option: B
Explanation:

Law of inertia states that the body tends to remain in the same state (regarding its velocity and direction) untill no external force is acting on it.

Hence option B is correct.

Which of the following equations or principle is most suitable to solve given question.  

A block of mass $m$ remains at rest on a table when a piece of paper is pulled out from under 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. Newton's first law(law of inertia)

  2. Newton's second law ($F _{net}$ = ma)

  3. Newton's third law (For every action there is an equal and opposite reaction)

  4. Newton's law of universal gravitation

  5. Conservation of linear momentum

Show answer
Correct Option: A
Explanation:

Newton's First Law of Motion - sometimes referred to as the 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 force.

Hence a piece of mass remains at rest on a table when a piece of paper is suddenly pulled out from under it.

If no force acts on a body, then what will happen to 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. It does not change its shape.

  2. It continues to move but with less speed.

  3. It changes its direction.

  4. It can either remain at rest or continue to move in a straight line.

Show answer
Correct Option: D
Explanation:
The force is define as $F=ma$
hence acceleration is $a=\dfrac{F}{m}$
if  balanced force acts on a body F is  zero hence body must not be accelerated. hence by eq of motion $u=v=at,a=0\implies u=v$ if v=0,u=0
It can either remain at rest or continue to move in a straight line.

Physical independence of force is a con-sequence of 'X'. Identify 'X'.

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 third law of motion

  2. Newton's second law of motion

  3. Newton's first law of motion

  4. All of the above

Show answer
Correct Option: C
Explanation:

Physical independence of force is a con-sequence of 'X'.

X is Newton's first law of motion Newton's first law of motion - sometimes referred to as the law of inertia. 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 force

State whether true or false.
Newton's first law of motion gives the concept of momentum.

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:

No the given statement is false at newton first law of motion gives the concept of inertia while the concept of momentum was given by second law.

State whether true or false.
A ball thrown upwards in a train moving with uniform velocity returns to the thrower. 
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:

Since train is moving with uniform velocity so when the thrower throws the ball upward ball has already acquire the same velocity as that of moving train and have moved the same distance as that of thrower. 

When a bus suddenly takes a turn, the passengers are thrown outwards 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. Inertia of motion

  2. Acceleration of motion

  3. Speed of motion

  4. Both (b) and (c)

Show answer
Correct Option: A
Explanation:

According to law of inertia of motion a body will continue moving with constant velocity until unless any force is acting on it. When a bus is moving straight the passengers inside are also moving straight but when suddenly bus turn left passengers still continue to move straight  because no force is acting on passengers so they will move with same magnitude and direction i.e. outwards when bus turns .

Which Newton's law of motion defines 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. First

  2. Second

  3. Third

  4. None

Show answer
Correct Option: A
Explanation:

Newton's first law of motion gives definition of force.

Newtons law are not valid in

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

  1. Both inertial as well as non- inertial frame of reference.

  2. A frame moving with constant velocity w.r.t. an inertial frame.

  3. All reference frames which are at rest w.r.t. an inertial frame.

  4. The reference frame attached to the earth.

Show answer
Correct Option: A
Explanation:

Newton's Law is only valid in inertial frame of reference. If there is a non - inertial frame of reference then it won't be valid. 

Hence option $\textbf A$ is the correct answer.

A force vector applied on a mass is represented by $\vec {F} = 6\hat {i} - 8\hat {j} + 10\hat {k}$ and accelerates with $1\ m/s^{2}$. What is the mass of the body?

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

  1. $14\ kg$

  2. $10\sqrt {2}kg$

  3. $2\sqrt {10}kg$

  4. $20\ kg$

Show answer
Correct Option: A
Explanation:
To find mass of the body we will use magnitude of force formula $,$ 
According to question$:-$
$\overrightarrow { F } =6-8\widehat { j } +10\widehat { k } $
Magnitude of Force $=\sqrt {\left( {{6^2} + {8^2} + {{10}^2}} \right)} $
                                  $= 14.14 N$
$m = F / a$
     $= 14.14 N / 1 m/s^2$
     $= 14.14 kg$
Hence,
option $(A)$ is correct answer.