Tag: concept of force and its unit

Questions Related to concept of force and its unit

$1\ gf$

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

  1. $105\ dyne$

  2. $981\ dyne$

  3. $9.8\ N$

  4. $1\ N$

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Correct Option: B
Explanation:

Force, $F = mg$    where $m = 1$ gram  and $g = 981$ $cm/s^2$

$\therefore$  $1$ $gf = 1\times 981   =981$ $dyne$  where dyne is a cgs unit of force

Which is correct for balanced and unbalanced forces?

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

  1. If set of forces acting on body results in change in state such forces are called unbalanced forces

  2. The vector sum of all forces is zero i.e. $\sum Fx = 0$

  3. The object is in non-equilibrium state and the resultant force is non-zero. i.e. $\sum Fx \neq 0$

  4. All

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Correct Option: D
Explanation:

If a set of forces acting on a body does not change the state of rest or of motion of an object such forces are called balanced forces. In this case object is said to be in equilibrium state. The vector sum of all forces is zero i.e. $\sum Fx = 0$.
Set of forces acting on body results in change in state i.e. either changes the speed or direction, such forces are called unbalanced forces.  In this case the object is in non-equilibrium state and the resultant force is non-zero. i.e. $\sum Fx \neq 0$.

Which is not the non-SI unit of force

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

  1. $Dyne$

  2. $Kg - force$

  3. $Gram - force$

  4. $kg\ m/s^{2}$

Show answer
Correct Option: D
Explanation:
Force       $F  = ma$
SI unit of force is  $kg$ $m/s^2$ or Newton $(N)$ 
Whereas the rest are non-SI units of force.

The force acting on an object are balanced, then the object:

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

  1. must be at rest

  2. must be moving

  3. must not be accelerating

  4. must lose energy

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Correct Option: C
Explanation:

Balanced forces always result in a zero external force acting on an object  i.e  $F _{ext}  =0$

$\therefore$   Acceleration       $a  = \dfrac{F _{ext}}{m}  =  0$
Thus the object must not be accelerating or it must be moving with constant velocity or remain at rest (if it was at rest initially). Hence option C is correct.

In tug of war, there are teams A and B. A applies $200 N$ force and B applies $1000 N$ force. Choose the correct statement(s).

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

  1. The rope will stay at the same place.

  2. The rope will break.

  3. Rope will be drawn towards A.

  4. Rope will be drawn towards B.

Show answer
Correct Option: D
Explanation:

Force applied by team A:        $F _A = 200\ N$           (towards A)

Force applied by team B:        $F _B = 1000\ N$         (towards B)

Net force, $F _{net} = F _B-F _A = 1000-200  =800\ N$        (towards B)

What kind of force is required to accelerate the motion of an object?

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

  1. Balanced force

  2. Unbalanced force

  3. Pressurized force

  4. Equal and opposite force

Show answer
Correct Option: B
Explanation:

Unbalanced forces produce a resultant force acting on the object in a particular direction which tends the object to accelerate in that particular direction.

On a body, a force of $5N$ is applied towards North and another force of $2N$ is applied towards South. Net force on the body is

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

  1. $3N$

  2. $7N$

  3. $5N$

  4. $2N$

Show answer
Correct Option: A
Explanation:

When forces are applied inn the opposite directions, the forces get subtracted.
So, net force on the body$=(5-2)N=3N$

To pull a heavy goods' train, two engines are often connected one after another. This is to

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

  1. increase the pull

  2. decrease the pull

  3. save the power

  4. do none of these

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Correct Option: A
Explanation:

Two engines set one after another will increase the pull.

To move a roller, a force of $300 N$ is required. You alone can produce a force of $30 N$. How many of your friends who are equally strong as you should join you to move the roller?

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

  1. 9

  2. 10

  3. 5

  4. None of these

Show answer
Correct Option: A
Explanation:

Force applied by you $= 30 N =$ force applied by any of your friends.
So, let there be $x$ people in total to push the roller.
When $x$ people, each giving a force of $30N$, give force in same direction, total force = $30xN$
To move the roller, $30x=300$
So, $x=\frac{300}{30}=10$
$\therefore$ number of friends to join you $=(10-1)=9$

You are pushing a ball. If your younger sister pushes it from the opposite side with lesser force, the ball will

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

  1. move slower

  2. move faster

  3. move at same speed

  4. move in another direction

Show answer
Correct Option: A
Explanation:

When forces are applied from opposite directions, the forces get subtracted. So, the resultant or net force is less than the force which you were applying initially. As a result, the ball will move at a slower speed.