Tag: concept of force and its unit

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

A particle is moving along x-axis under the action of a force, $F$ which varies with its postion (x) as $F \propto x^{-1/4}$. The variation of power due to this force with $x$ is

  1. $x^{\dfrac{1}{3}}$

  2. $x^{\dfrac{1}{8}}$

  3. $x^{\dfrac{1}{2}}$

  4. $x^{\dfrac{1}{4}}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice physics force concept of force and its unit force - push or pull forces

A rope of mass $ 5 kg$ is moving vertically in vertical position with an upwards force of $100$ $N$ acting at the upper end and a downwords force of $70$$N$ acting at the lower end The tension at midpoint of the rope is

  1. $100 N$

  2. $85 N$

  3. $75 N$

  4. $105 N$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The net force on the rope is 100 N - 70 N = 30 N. The mass is 5 kg, so acceleration a = F_net / m = 30 / 5 = 6 m/s^2 upwards. For the bottom half (mass 2.5 kg), the forces are Tension T and gravity (2.5 * 10 = 25 N). T - 25 = m_half * a = 2.5 * 6 = 15. Thus, T = 40 N. Wait, re-evaluating: The force at the midpoint is the average of the forces at the ends if the rope is uniform and acceleration is constant. (100 + 70) / 2 = 85 N.

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

When you and your friend pushed heavy table in the same direction , it becomes easier to move. This is because:

  1. The net force is the sum of forces.

  2. The net force is the difference of force.

  3. The net force is division of forces.

  4. The net force is multiplication of forces. 
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If two forces act on an object in the same direction, the net force is equal to the sum of the two forces. This always results in a stronger force than either of the individual forces alone.

Hence, the net force is the sum of forces

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

Two forces P and Q can support the body of weight W, one by one, when the body is on the inclined plane of inclination $\theta$ with horizontal and P and Q are acting parallel to the length and base of the inclined plane respectively. Hence

  1. $P^{2} + Q^{2} = W^{2}$

  2. $P^{2} - Q^{2} = W^{2}$

  3. $\cfrac{1}{P^{2}} + \cfrac{1}{Q^{2}} = \cfrac{1}{W^{2}}$

  4. $\cfrac{1}{P^{2}} - \cfrac{1}{Q^{2}} = \cfrac{1}{W^{2}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics force concept of force and its unit force - push or pull forces

A 200 g of putty ball falls vertically into a 2.5 kg cart that is rolling freely at 2 m/s on a horizontal surface. What is the final speed of the cart?

  1. $11.85 m/s$

  2. $1.85 m/s$

  3. $10.85 m/s$

  4. $2.85 m/s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using conservation of momentum: m1 * v1 + m2 * v2 = (m1 + m2) * v_final. Here, 2.5 * 2 + 0.2 * 0 = (2.5 + 0.2) * v_final. 5 = 2.7 * v_final. v_final = 5 / 2.7 = 1.8518 m/s.

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

You want to lift a heavy box. The force of gravity pulls it downwards with a force of $500N$. Your father applies an upward force of $220 N$ from below. How much force will you have to apply to lift it upwards?

  1. $720 N$

  2. $280 N$

  3. $180 N$

  4. $380 N$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The force of the gravitational pull is 500 N and the additional force of 220 N is applied in the opposite direction.
So, to lift the box, the box has to apply an extra force of 500 N - 220 N = 280 N in order to lift the box against the gravitational pull.
Resultant force is nothing but the total force acting on a body including their directions. Here, the gravitational force acts opposite to the force applied by the father and the boy.
Hence, the boy has to apply a force of 280 N to lift the box.

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

The strength of a force is usually expressed by its:

  1. unit

  2. magnitude

  3. direction

  4. both unit and magnitude.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A force could be larger or smaller than the other and the strength of the force is expressed by its magnitude only. For example, $1\ N$ of force is larger than $1\ mN$ of force.

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

What will be the net force acting on an object when two equal forces are applied on an object in opposite directions?

  1. Sum of the forces.

  2. Zero

  3. Equal to each of the applied forces.

  4. Difference of the forces.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The forces acting on the object in the opposite directions are equal. The net force will be the difference of the two equal forces. Since both the forces are equal, net force is zero.