Online Test For Class 11 Physics Laws of Motion

class 11 physics

Practice class 11 physics chapter 5 Laws of Motion objective type questions through this online test. This is a very important chapter for preparation of competitive exams point of view.

Laws of Motion Online MCQ Test

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General Instructions

Your test contains multiple-choice questions with only one answer type questions. There are a total of 25 questions
This is a 45 min test. Please make sure you complete it in stipulated time
You can finish this test any time using the 'Submit' button.

1. Two particles of masses $m_1$ and $m_2$ in projectile motion have velocities $\vec{v_1}<\vec{v_2}$ respectively at time $t=0$. Thet collide at time $t_0$ . Their velocities become $\vec{v'_1}$ and $\vec{v'_2}$ at time $2t_0$, while still moving in air. The value of $\left|\left(m_1\vec{v'_1}+m_2\vec{v'_2}\right)-\left(m_1\vec{v_1}+m_2\vec{v_2}\right)\right|$ is

$\left(m_1+m_2\right)gt_0$

$2\left(m_1+m_2\right)gt_0$

$\frac{1}{2}\left(m_1+m_2\right)gt_0$

zero

2. A string of negligible mass going over clamped pully of mass supports block of mass as shown in the figure.

The force on the pully by clamp is given by

$\sqrt{2}Mg$

$\sqrt2mg$

$\sqrt{\left(M+m\right)^2+m^2}g$

$\sqrt{\left(M+m\right)^2+M^2}g$

3. When a bicycle is in motion, the force of friction exerted by ground on the two wheels is such that, it acts

in the backward direction on the front wheel and in the forward direction on the rear wheel.

in the forward direction on the front wheel and in the backward direction on the rear wheel.

in the backward direction on both the front and the rear wheel.

in the forward direction on both front and the rear wheels.

4. A rocket with a lift-off mass $3.5\times{10}^4Kg$ is blasted upwards with an initial acceleration of $10m/s^2$. Then the initial thrust blast is

$3.5\times{10}^5N$

$7.0\times{10}^5N$

$14.0\times{10}^5N$

$1.75\times{10}^5N$

5. 5 The block of mass $M$ is pulled along a horizontal frictionless surface by a rope of mass $m$. If a force $P$ is applied at the free end of the rope, the force exerted by the rope on the block is

$\frac{Pm}{\left(M+m\right)}$

$\frac{Pm}{\left(M-m\right)}$

$P$

$\frac{PM}{\left(M+m\right)}$

6. Three forces start action simultaneously on a particle moving with velocity $\vec{v}$. These forces are

Represented in magnitude and direction by the three sides of a triangle $ABC$ as shown in the figure. The particle will now move with velocity

greater than $\vec{v}$

$\left|\vec{v}\right|$ in the direction of the largest force $BC$

$\vec{v}$ remaining unchanged

less than $\vec{v}$

7. A lift is moving down with acceleration a. A man in the lift drops a ball inside the lift. The acceleration of the ball is observed by the man in the lift and a man standing stationary on the ground are respectively.

$g,g$

$g-a, g-a $

$g-a, g$

$a,g$

8. A light spring balance hangs from the hook of the other light spring balance and a block of mass $M\, Kg$ hangs from the former one. Then the true statement about the scale reading is

Both the scales read $M\, Kg$ each

The scale of the lower one read $M\, Kg$ and of the upper one zero.

The reading of the two scales can be anything but the sum of readings will be $M\, Kg$

Both the scales read $M/2\, Kg$

9. A block rests on a rough inclined plane making an angle of ${30}^0$ with the horizontal. The coefficient of static friction between the block and the plane is $0.8$. If the frictional force on the block is $10\, N$, the mass of the block (in Kg) $\left(g=10m/s^2\right)$ is

2.0

4.0

1.6

2.5

10. A horizontal force of is necessary to just hold a block stationary against a wall. The coefficient

Of friction between the block is 0.2. The weight of the block is

20 N

50 N

100 N

2 N

11. A smooth block is released at rest on a ${45}^0$ incline and then slides a distance $d$. The time taken to slide is $n$ times as much to slide on a rough incline than on a smooth incline. The coefficient of friction is

$\mu_k=1-\frac{1}{n^2}$

$\mu_k=\sqrt{1-\frac{1}{n^2}}$

$\mu_s=1-\frac{1}{n^2}$

$\mu_s=\sqrt{1-\frac{1}{n^2}}$

12. A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane. It follows that

the velocity is constant

its acceleration is constant

its kinetic energy is constant

it moves in a straight line

13. An annular ring with inner and outer radii $R_1$ and $R_2$ is rolling without slipping with a uniform angular speed. The ratio of the forces $F_1/F_2$ experienced by two identical particles situated on the inner and outer parts of the ring is

$\frac{R_2}{R_1}$

$\left(\frac{R_1}{R_2}\right)^2$

$1$

$\frac{R_1}{R_2}$

14. Two frictionless inclined planes making angles ${30}^0$ and ${60}^0$ with the vertical are shown in the figure. Two blocks A and B are placed on two planes

What is the relative vertical acceleration of A with respect to B?

$4.9m/s^2$ in vertical direction

$4.9m/s^2$ in horizontal direction

$9.8m/s^2$ in the vertical direction

zero

15. Question 15 Which of the four arrangements in the figure correctly shows the vector addition of two forces $F_1$ and $F_2$ to yield the third force $F_3$

16. A body of mass 5 Kg starts from the origin with an initial velocity $\vec{u}=\left(30\hat{i}+40\hat{j}\right) m/s$. If a constant force $\left(-6\hat{i}-5\hat{j}\right)N$ acts on the body, the time in which y component of velocity becomes zero is

5 s

20 s

40 s

80 s

17. Three blocks of mass 2 Kg, 3Kg, 5 Kg are connected to each other with a light string and are then placed on a frictionless surface as shown in the figure. The system is pulled by a force $F=10\, N$, then tension $T_1$ is

1 N

5 N

8 N

10 N

18. A particle is moving in a circle with uniform speed $v$. In moving from a point to another diametrically opposite point,

the momentum changes by $mv$

the momentum changes by $2mv$

the kinetic energy changes by $\frac{1}{2}mv^2$

the kinetic energy changes by $mv^2$

19. A person is sitting in a lift accelerating upwards. The measured weight of a person will be,

less than actual weight

equal to actual weight

more than actual weight

zero

20. Which of the following statements is true?

velocity of light is constant in all media

velocity of light in vacuum is maximum

velocity of light is same in all reference frames

Laws of nature have identical form in all reference frames.

21. In following question, a statement of assertion is followed by a statement of reason. Mark the correct choice.
Assertion: A rocket moves forward by pushing surrounding air backwards.
Reason: It derives the necessary thrust to move forward, according to Newton’s third law of motion.

If both assertion and reason are true and reason is the correct explanation of assertion

If both assertion and reason are true but reason is not correct explanation of assertion.

If assertion is true and reason is false.