Tag: concept of force and its unit

Questions Related to concept of force and its unit

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

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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

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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. 

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

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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.