Tag: physics

Questions Related to physics

Force is _______. Fill in the blank.
physics force and types of force concept of force and its unit force - push or pull forces

  1. a push

  2. a pull

  3. both A and B

  4. none of these

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Correct Option: C
Explanation:

Force is a push or pull which changes or tends to change the state of rest or of uniform motion.

A force can change:

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

  1. shape of a body

  2. size of a body

  3. direction of motion

  4. all the above

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Correct Option: D
Explanation:

A force can change or tend to change shape, size of a body or its state of rest or direction of motion.

Which of the following is/are contact forces

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

  1. Normal force

  2. Tension force

  3. Friction force

  4. All

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Correct Option: D
Explanation:

Contact forces are those types of forces which result when the two interacting objects are perceived to be physically contacting each other. Examples of contact forces include frictional forces, tensional forces, normal forces, air resistance forces, and applied forces.

In order to apply a force on the body:

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

  1. there has to be an interaction.

  2. there must be no interaction.

  3. sometimes there may be an interaction.

  4. None of these

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Correct Option: A
Explanation:

Two bodies must interact in order to apply a force.

In which following events is a pushing force involved?

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

  1. Badminton

  2. Javelin

  3. Archery

  4. Bowling

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Correct Option: A,B,C,D
Explanation:

All Options are correct, as in each sports, Badminton racket, Javelin, bowling ball is pushed.

Also, in Archery, string pushes the arrow.

Which of the following pairs of forces cannot be added to give a resultant force of $4N$?

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

  1. $2 N$ and $8 N$

  2. $2 N$ and $2 N$

  3. $2 N$ and $6 N$

  4. $2 N$ and $4 N$

Show answer
Correct Option: A
Explanation:

Resultant force, 

$F=\sqrt{F _1^2+F _2^2+2F _1F _2cos\theta}$. . . . . . . . .(1)
Lets consider the option A,

$F _1=2N$
$F _2=8N$

For maximum resultant force, $cos\theta=1$
From equation (1),
$F _{max}=\sqrt{F _1^2+F _2^2+2F _1F _2}=\sqrt{(F _1+F _2)^2}$
$F _{max}=F _1+F _2$
$F _{max}=8+2=10N$
For minimum resultant force, $cos\theta=-1$
$F _{min}=\sqrt{F _1^2+F _2^2-2F1F _2}=\sqrt{(F _1-F _2)^2}$
$F _{min}=\sqrt{(2-8)^2}=6N$
So, the $4N$ does not lie within this range. Thus it is not possible to have it as resultant force.
The correct option is A.

Two forces 12 N and 5 N are acting perpendicular to each other. Then the net force acting is.

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

  1. 17 N

  2. 18 N

  3. 7 N

  4. zero

  5. 13 N

Show answer
Correct Option: E
Explanation:

$ \vec F _{net} = \vec F _1 +\vec F _2$

$| \vec F _{net}| = \sqrt{F _1^2 +F _2^2 +2F _1F _2\cos\theta}$
$| \vec F _{net}| = \sqrt{12^2 +5^2 +2\times 12 \times 5\cos 90^0}$
$| \vec F _{net}| = \sqrt{12^2 +5^2 }$
$| \vec F _{net}| = 13N$
Therefore, E is correct option.

Two forces of $12 \mathrm { N } \text { and } 8 \mathrm { N }$ acts upon a body. The resultant force on the body has maximum value of

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

  1. $4 \mathrm { N }$

  2. $0 \mathrm { N }$

  3. $20 \mathrm { N }$

  4. $8 \mathrm { N }$

Show answer
Correct Option: C
Explanation:

Given,

$|\vec F _1|=12N$
$|\vec F _2|=8N$

The resultant force on the body is 
$|\vec R|=\sqrt{F _1^2+F _2^2+2F _1F _2cos\theta}$

For maximum value, $cos\theta=1$
$|\vec R|=\sqrt{(12)^2+(8)^2+2\times 12\times 8\times 1}$

$|\vec R _{max}|=\sqrt{144+64+24\times 8}$

$|\vec R _{max}|=\sqrt{400}=20N$
The correct option is C.

Fill in the blanks:
The net force is ______ than the individual applied forces.

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

  1. either larger or smaller

  2. always smaller

  3. always greater

  4. always equal

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Correct Option: A
Explanation:

The net force is either sum or difference of individual applied forces. So, the force is either larger or smaller than individual forces.

In tug of war, if the two teams have equal strength then:

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

  1. the rope will break.

  2. the rope will stay at the same place.

  3. the rope will move towards one of the sides.

  4. the rope will move towards each end alternatively.

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Correct Option: B
Explanation:

The rope breaks only if the force applied by both the teams is very large. It has nothing to do with the equality of the strength in the teams on the two sides of the rope.
In a tug of war, if the two teams are applying equal force on the rope then the net force acting on the rope is zero and hence the rope stays at the same place.