Laws of Motion Quiz - ICSE Class 11 Physics

Free practice quiz: Laws of Motion (ICSE Class 11 Physics). 48 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 11 Physics practice quiz has 48 multiple-choice questions on Laws of Motion, and 48 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. A block of mass $m$ is at rest on a rough inclined plane. If the angle of inclination is $\theta$, and the coefficient of static friction between the block and the plane is $\mu_s$, what is the condition for the block to remain at rest?

   1. $mg \sin \theta > \mu_s mg \cos \theta$
   2. $mg \sin \theta < \mu_s mg \cos \theta$
   3. $mg \sin \theta \le \mu_s mg \cos \theta$
   4. $mg \sin \theta = \mu_s mg \cos \theta$
   Show answer

   Answer: C. $mg \sin \theta \le \mu_s mg \cos \theta$

   For the block to remain at rest, the component of gravity down the incline ($mg \sin \theta$) must be less than or equal to the maximum static friction force ($\mu_s N$, where $N = mg \cos \theta$ is the normal force). Thus, $mg \sin \theta \le \mu_s mg \cos \theta$.

2. A particle is moving in a straight line with constant acceleration. If its initial velocity is $u$ and its displacement after time $t$ is $s$, which of the following equations is NOT one of the standard kinematic equations?

   1. $s = ut + \frac{1}{2}at^2$
   2. $v = u + at$
   3. $v^2 = u^2 + 2as$
   4. $s = vt - \frac{1}{2}at^2$
   Show answer

   Answer: D. $s = vt - \frac{1}{2}at^2$

   The standard kinematic equations for constant acceleration are $v = u + at$, $s = ut + \frac{1}{2}at^2$, and $v^2 = u^2 + 2as$. The equation $s = vt - \frac{1}{2}at^2$ is derived from $v = u+at \implies u = v-at$, and substituting this into $s = ut + \frac{1}{2}at^2$, giving $s = (v-at)t + \frac{1}{2}at^2 = vt - at^2 + \frac{1}{2}at^2 = vt - \frac{1}{2}at^2$. While it can be derived, it's typically not listed as a primary kinematic equation derived directly from definitions.

3. A block of mass $m$ is placed on a smooth horizontal surface. If a horizontal force $F$ is applied, the block accelerates. What is the acceleration of the block if a second identical block is placed next to it, and the same force $F$ is applied to the combined mass?

   1. Same as before
   2. Twice the previous acceleration
   3. Half the previous acceleration
   4. Depends on the distance between the blocks
   Show answer

   Answer: C. Half the previous acceleration

   In the first case, $a_1 = F/m$. In the second case, the total mass is $2m$, and the force is still $F$. So, the acceleration is $a_2 = F/(2m) = \frac{1}{2} (F/m) = \frac{1}{2} a_1$. The acceleration is halved.

4. If a body moves with constant velocity, what is the work done by the net force on the body?

   1. Positive
   2. Negative
   3. Zero
   4. Cannot be determined
   Show answer

   Answer: C. Zero

   Constant velocity implies zero acceleration. By Newton's second law ($F_{net} = ma$), if acceleration is zero, the net force must be zero. Work done by the net force is $W_{net} = F_{net} \cdot d$. If $F_{net} = 0$, then $W_{net} = 0$. Alternatively, the work-energy theorem states that the net work done equals the change in kinetic energy. If velocity is constant, kinetic energy is constant, so the change in kinetic energy is zero, hence the net work done is zero.

5. A block of mass $m$ is on a horizontal surface. A force $F$ is applied horizontally. If the block is just about to move, the frictional force is:

   1. Zero
   2. Equal to $F$
   3. Equal to $\mu_s N$
   4. Greater than $F$
   Show answer

   Answer: B. Equal to $F$

   When a body is at rest, the static friction force adjusts itself to be equal in magnitude and opposite in direction to the applied force, up to a maximum value ($\mu_s N$). If the block is 'just about to move', it means the applied force $F$ is equal to the maximum static friction, and the static friction force itself is equal in magnitude to this applied force.

More questions in this quiz

Answers and explanations are in the full quiz.

1. A projectile is launched with initial velocity $v_0$ at an angle $\alpha$ with the horizontal. What is the maximum height reached by the projectile, assuming no air resistance?
2. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. If object A exerts a force on object B, what can be said about the force exerted by object B on object A?
3. A 10 kg block is pulled horizontally with a constant force of 50 N on a frictionless surface. What is the acceleration of the block?
4. A car of mass $m$ moving with velocity $v$ suddenly stops. The momentum of the car before stopping is $p_1$ and after stopping is $p_2$. The change in momentum is:
5. A body is projected vertically upwards with an initial velocity $u$. When it reaches the maximum height, its velocity is:
6. If a force of 10 N acts on a body of mass 2 kg, causing an acceleration of 5 m/s², what is the magnitude of the frictional force acting on the body?
7. A force $\mathbf{F}$ is applied to a block of mass $m$ resting on a horizontal surface. The force is applied at an angle $\theta$ below the horizontal. The normal force exerted by the surface on the block is:
8. What is the unit of impulse in the SI system?
9. A block of mass 5 kg is moving on a horizontal surface with a velocity of 10 m/s. If a retarding force of 20 N acts on it, how long will it take to stop?
10. Which of the following statements about the coefficient of friction is INCORRECT?
11. A body of mass $m$ is moving with a constant velocity $v$. If a force $F$ is applied to it, and the net force on the body becomes $F_{net}$, what is the acceleration of the body?
12. A ball is thrown horizontally from the top of a building with a velocity $v_x$. If air resistance is negligible, what is its vertical velocity just before it hits the ground?
13. Consider a situation where an object is moving in a circle at a constant speed. What is the direction of the net force acting on the object?
14. A spring of spring constant $k$ is stretched by a distance $x$ from its equilibrium position. The force exerted by the spring is given by Hooke's Law. Which of the following statements is true?
15. A body is moving with constant momentum. What can be concluded about the net force acting on the body?
16. When a car turns a corner on a level road, the force that provides the necessary centripetal acceleration is typically:
17. A 2 kg object is moving with a velocity of 4 m/s. A force acts on it for 3 seconds, and its velocity becomes 10 m/s. What is the magnitude of the average force acting on the object?
18. What is the magnitude of the centripetal acceleration of a particle of mass $m$ moving with speed $v$ in a circular path of radius $r$?
19. A body of mass 5 kg is at rest. A constant force of 10 N is applied to it. If the force acts for 5 seconds, what will be the final velocity of the body?
20. A block is placed on a rough inclined plane that makes an angle $\theta$ with the horizontal. The block is released and starts sliding down. The acceleration of the block is given by $a = g(\sin \theta - \mu_k \cos \theta)$, where $\mu_k$ is the coefficient of kinetic friction. If the plane is frictionless, what is the acceleration?
21. Consider the conservation of linear momentum. If no external forces act on a system of particles, then:
22. A block is subjected to a net force $F$. If the mass of the block is doubled, what happens to its acceleration, assuming the net force remains the same?
23. What is the condition for a body to be in translational equilibrium?
24. A car of mass $m$ is moving at a constant speed $v$ on a level road. If the driver applies the brakes, and the car comes to rest in time $t$, what is the magnitude of the average braking force?
25. A projectile is launched with initial velocity $v_0$ at an angle $\alpha$ with the horizontal. What is the horizontal range of the projectile, assuming no air resistance and launch and landing at the same height?
26. A block is at rest on a horizontal frictionless surface. If a force $F$ is applied, and then removed, what happens to the block's motion?
27. The unit of power in the SI system is:
28. A body of mass $m$ is thrown vertically upwards with an initial velocity $u$. Ignoring air resistance, what is the velocity of the body when it returns to the point of projection?
29. What is the impulse-momentum theorem?
30. A mass $m$ is attached to a spring with spring constant $k$. If the mass is displaced from its equilibrium position and released, it undergoes simple harmonic motion. What is the frequency of this oscillation?
31. When a person jumps from a height onto a hard surface, they tend to bend their knees upon landing. This action primarily serves to:
32. A block of mass $m$ is pulled by a constant force $F$ at an angle $\theta$ above the horizontal. The block moves with constant velocity $v$. What is the coefficient of kinetic friction $\mu_k$ between the block and the surface?
33. Two particles of mass $m_1$ and $m_2$ are moving towards each other with velocities $v_1$ and $v_2$ respectively. They undergo a perfectly elastic collision. What is the total momentum of the system after the collision?
34. A person is standing on a weighing scale in an elevator. When the elevator accelerates upwards, the reading on the weighing scale will:
35. Which of the following is a vector quantity?
36. A body starts from rest and moves with constant acceleration $a$. After time $t$, its velocity is $v$. What is the average velocity during this time interval?
37. If the distance covered by a particle is zero, then its displacement:
38. A force of 100 N is applied to a 10 kg block. If the block is on a rough surface with a coefficient of kinetic friction of 0.2, what is the net force acting on the block if it moves horizontally?
39. Which of the following is an example of Newton's first law of motion (Law of Inertia)?
40. A projectile is launched with an initial velocity $v_0$ at an angle $\alpha$ to the horizontal. The horizontal component of its velocity remains constant throughout its flight if we neglect air resistance. This is because:
41. A body of mass $m$ is sliding down a rough inclined plane with angle of inclination $\theta$. The coefficient of kinetic friction is $\mu_k$. What is the acceleration of the block?
42. If a net force of 100 N acts on a body for 5 seconds, causing a change in momentum of 500 kg·m/s, what is the acceleration of the body?
43. A body is moving in a straight line with a constant acceleration. Which of the following statements is NOT necessarily true?

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