Tag: physics

Questions Related to physics

When no force acts on a body , it must be _______.

physics along with motion what forces can do? force and it's unit force and its effects

  1. Moving

  2. At rest

  3. In uniform motion

  4. Either B or C

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Correct Option: D
Explanation:

Both in uniform motion and when the body is at rest the net force on the body is zero or the body is said to be in equilibrium.

If we apply the brakes to a moving car, it comes to rest. This shows that force can make a moving object go slower.

physics along with motion what forces can do? force and it's unit force and its effects

  1. True

  2. False

  3. Ambiguous

  4. Data insufficient

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Correct Option: A
Explanation:

Answer is A.

Friction prevents objects from moving or slows them down. It also causes wear on surfaces as they rub against each other and generates heat. Thus energy is wasted in overcoming friction. Hence, the force of friction can slow down an object.
Hence, the statement is true.

Eqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force ?

physics along with motion what forces can do? force and it's unit force and its effects

  1. Eqbal

  2. Seema

  3. Both apply same force

  4. cant say

Show answer
Correct Option: B
Explanation:

Force of friction arises because of interlocking of irregularities on the two surfaces in contact. When a heavy object is placed on the floor, the interlocking of irregularities on the surface of box and floor become strong. This is because the two surfaces in contact are pressed harder. Hence, more force is required to overcome the interlocking. Thus to push the heavier box, Seema has to apply a greater force than Eqbal.

State whether true or false.
If a body is moving with a constant speed along a straight line, then in order to change its direction of motion, an external force or its component has to act in a direction normal to the direction of motion.

physics along with motion what forces can do? force and it's unit force and its effects

  1. True

  2. False

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Correct Option: B
Explanation:

Here, body is moving with constant velocity. 

To change its direction of motion,  an external force must act in the direction opposite to the velocity, so given statement is false. 

In which of the following cases, the net force acting on the body is not zero?

physics along with motion what forces can do? force and it's unit force and its effects

  1. An object floating in mercury

  2. A ball freely falling from a certain height

  3. A cork floating on the surface of water.

  4. All of the above cases.

Show answer
Correct Option: B
Explanation:

In the case of falling freely under gravity.

  By newton second law
 $F _{net}=ma$
in this case $a=(-g)$
Hence there is net force in downward direction.
Rest are all balanced.

Two bodies of masses ${m} _{1}$ and ${m} _{2}$ are acted upon by a constant force $F$ for a time $t$. They start from rest and acquire kinetic energies ${E} _{1}$ and ${E} _{2}$ respectively. Then $\dfrac{{E} _{1}}{{E} _{2}}$ is

physics along with motion what forces can do? force and it's unit force and its effects

  1. $\dfrac{{m} _{1}}{{m} _{2}}$

  2. $\dfrac{{m} _{2}}{{m} _{1}}$

  3. $1$

  4. $\dfrac{\sqrt{{m} _{1}{m} _{2}}}{{m} _{1}+{m} _{2}}$

Show answer
Correct Option: B
Explanation:

Bodies of mass $m _1$ and $m _2$ acted on by force F (say) for time t. Acceleration in mass $m _1$= $\dfrac{F}{m _1}$
Acceleration in mass $m _2$= $\dfrac{F}{m _2}$
Velocity acquired during this time for mass $m _1$
$v _1=\dfrac{F}{m _1} t$
Velocity acquired during this time for mass $m _2$
$v _2=\dfrac{F}{m _2} t$

Ratio of kinetic energy acquired
$\dfrac{E _1}{E _2}=\dfrac{\dfrac{1}{2}m _1v _1^2}{\dfrac{1}{2}m _2v _2^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _1\times (\dfrac{F}{m _1} t)^2}{m _2\times (\dfrac{F}{m _2} t)^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _2}{m _1}$

If $f(x) = \dfrac {1}{\sqrt {2\pi}} e^{-\dfrac {x^{2}}{2}}$, then for which of the following values of $x$ does $f(x) = 0.33$?

physics along with motion what forces can do? force and it's unit force and its effects

  1. $0.62$

  2. $0.71$

  3. $1.36$

  4. $3.93$

  5. $4.95$

Show answer
Correct Option: A

A force is a result of:

physics force and types of force concept of force and its unit force - push or pull forces

  1. interaction between two bodies

  2. interaction of one body with itself

  3. friction

  4. all of the above

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Correct Option: A
Explanation:

One object exerts a force on the other object due to their mutual interaction when the objects either are in contact with each other or placed at certain distance apart.

In which direction does a car at rest move when pushed by a few persons?

physics force and types of force concept of force and its unit force - push or pull forces

  1. In the direction opposite to push

  2. In the direction of the push

  3. Making an acute angle with the push

  4. None of the above

Show answer
Correct Option: B
Explanation:

To move a car, their must be interactions between the men and the car. The interaction is exerted in terms of push and the car moves in the direction of push, i.e., in the direction of the force applied.

Identify the type of force involved in opening the door of refrigerator.

physics force and types of force concept of force and its unit force - push or pull forces

  1. Pulling

  2. Pushing

  3. Heating

  4. Cooling

Show answer
Correct Option: A
Explanation:

The action involved to open the door of refrigerator is pulling the force is applied to pull the door of the refrigerator.