Tag: newton's first law of motion

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Questions Related to newton's first law 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
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.
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 rain drop of mass $0.1g$ is falling with uniform speed of $10{ cm/s }$. What is the net force the drop?

  1. ${ 10 }^{ -2 }N$

  2. ${ 10 }^{ -3 }N$

  3. $2\times { 10 }^{ -3 }N$

  4. $zero$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Uniform speed means that a body is traveling at a constant speed along a straight line. So it has no acceleration. Thus net weight $=ma=0$.

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 car driver going at a speed v suddenly find a wide wall at a distance. (coefficient of friction is $\mu $) 

  1. If the apply breaks, he will come to rest after a distance $\dfrac { { { v }^{ 2 } } }{ 2\mu g } $

  2. If he turn the cart in a circle to avoid hitting, then radius of the circle is $\dfrac { { { v }^{ 2 } } }{ \mu g } $

  3. It is better to apply breaks rather than to turn the vehicle in a circle

  4. It is better to turn the vehicle in a circle than to apply brakes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If he turn the cart in a circle to avoid hitting then radius of the circle is $\dfrac{{{v^2}}}{{2\mu g}}$
Option $B$ is correct answer.