Tag: forces

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Questions Related to forces

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

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

  1. In the direction&nbsp;<span>opposite&nbsp;to</span>&nbsp;push

  2. In the direction of the push

  3. Making an acute angle with the push

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

Which of the following is/are contact forces

  1. Normal force

  2. Tension force

  3. Friction force

  4. All
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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

  1. $2 N$ and $8 N$

  2. $2 N$ and $2 N$

  3. $2 N$ and $6 N$

  4. $2 N$ and $4 N$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. 17 N

  2. 18 N

  3. 7 N

  4. zero

  5. 13 N
Reveal answer Fill a bubble to check yourself
E Correct answer
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.