Tag: motion and rest

Questions Related to motion and rest

Two balls of different masses have the same KE. Then the: 

physics kinematics motion around us motion and rest moving things around us

  1. Heavier ball has greater momentum than the lighter ball.

  2. Lighter Will has greater momentum than the heavier ball.

  3. Both bans have equal momentum.

  4. Both balls have zero momentum.

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Correct Option: A
Explanation:

The relation between kinetic energy $(K)$ and momentum $(p)$ is given by, $K=\dfrac{p^2}{2m}$ where $m$ be the mass of the body

So, $p=\sqrt{2mK}$
As kinetic energy is constant, so $p\propto \sqrt m$
Thus, the heavier ball has more momentum than that of lighter ball. 

When a body is at rest, it is obeying

physics kinematics motion around us motion and rest moving things around us

  1. Principle of conservation of energy

  2. Principle of moments

  3. Newton's first law

  4. Newton's second law

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Correct Option: C
Explanation:
Inertia is the tendency of an object to remain at rest or in motion. Newton's First Law of Motion states that an object will remain at rest or move at a constant speed in a straight line unless it is acted on by an unbalanced force.
So, when a body is at rest, it is obeying Newton's first law or motion or law of inertia. 

An object is said to be in motion its position (with respect to another object)

physics kinematics motion around us motion and rest moving things around us

  1. changes with time

  2. does not change with time

  3. does not change

  4. is the same as before

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Correct Option: A
Explanation:

Changes with time

What is corrct statement about impulse?

physics along with motion motion around us motion and rest moving things around us

  1. change in velocity

  2. change in momentum due to force in small time

  3. change in acceleration

  4. change in speed

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Correct Option: B
Explanation:

Impulse:- It is defined as a change in momentum due to force in small time.

Mathematically, 
From Newton's law,
$F=\dfrac{\Delta p}{\Delta t}$
Impulse, $I=F\times \Delta t=\Delta P$
The correct option is B.

A train of length 200 m traveling at $30 { ms }^{ -1 }$ overtakes another train of length 300 m traveling at $20 { ms }^{ -1 }$. The time taken by the first train to pass the second is 

physics along with motion motion around us motion and rest moving things around us

  1. 10 s

  2. 30 s

  3. 40 s

  4. 50 s

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Correct Option: D

 A person in a car tends to fall back when it suddenly starts. It is due to

physics along with motion motion around us motion and rest moving things around us

  1. Inertia of rest

  2. Inertia of motion

  3. Inertia of direction

  4. none

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Correct Option: A
Explanation:

when bus suddenly start moving in forward direction. This happens due to. When a bus suddenly starts, the standing passengers fall backward in the bus.

It is due to inertia of rest.
Hence,

option $A$ is correct answer.

The wall of your classroom is in a state of -

physics along with motion motion around us motion and rest moving things around us

  1. motion

  2. rest

  3. neither rest nor motion

  4. none of these

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Correct Option: B
Explanation:

The walls are at rest with respect to the Earth. When you are sitting in the classroom, you are also at rest with respect to the Earth, and so the walls do not seem to be moving to you.

If the forces acting on an object are balanced, then_____

physics along with motion motion around us motion and rest moving things around us

  1. the object will be in equilibrium

  2. the object will be in motion

  3. the object will have zero acceleration

  4. the object loses its shape

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Correct Option: A,C
Explanation:

according to newton's first law of motion, 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.

so if forces acting on the object is balanced then the object will be in equilibrium and it will not have any acceleration.
cannot comment about option B because if initially object is at rest then it will be always at rest .
so best possible answer are option A,C.

If $\vec {u}=a \hat {i}+b \hat {j}+ c \hat {k}$ with $\hat {i},\hat {j},\hat {k}$ are in east, north and vertical directions, the maximum height of the projectile is ?

physics along with motion motion around us motion and rest moving things around us

  1. $\dfrac{a^{2}}{2g}$

  2. $\dfrac{b^{2}}{2g}$

  3. $\dfrac{c^{2}}{2g}$

  4. $\dfrac{b^{2} c^{2}}{2g}$

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Correct Option: C

When a body is at rest, it is obeying :

physics kinematics motion around us motion and rest moving things around us

  1. Principle of conservation of energy

  2. Newton's first law

  3. Ohm's law

  4. Newton's second law

Show answer
Correct Option: B
Explanation:

Newton's first law 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".Thus, body continues in it's state of rest as there is no external force on it,

So, option B is correct.