Tag: force and newton's laws of motion

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Questions Related to force and newton's laws of motion

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 law that gives a qualitative definition of force is :

  1. Newton's second law of motion

  2. Law of inertia

  3. Newton's third law of motion

  4. Law of gravitation
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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.

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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 no force acts on a body, then what will happen to it?

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.
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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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

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

  1. True

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

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

When a bus suddenly takes a turn, the passengers are thrown outwards because of 

  1. Inertia of motion

  2. Acceleration of motion

  3. Speed of motion

  4. Both (b) and (c)
Reveal answer Fill a bubble to check yourself
A Correct answer
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 .

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

Newtons law are not valid in

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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 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?

  1. $14\ kg$

  2. $10\sqrt {2}kg$

  3. $2\sqrt {10}kg$

  4. $20\ kg$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.