Laws of Motion & Friction · JEE Main previous year questions

2023 30 questions

1. Q322023 · 13 Apr 2023 · Shift 1

   A bullet of $10\text{ g}$ leaves the barrel of gun with a velocity of $600\text{ m/s}$. If the barrel of gun is $50\text{ cm}$ long and mass of gun is $3\text{ kg}$, then value of impulse supplied to the gun will be :

   1. A.$12\text{ Ns}$
   2. B.$3\text{ Ns}$
   3. C.$6\text{ Ns}$
   4. D.$36\text{ Ns}$
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   Answer: C

2. Q492023 · 13 Apr 2023 · Shift 1

   Two bodies are having kinetic energies in the ratio $16:9$. If they have same linear momentum, the ratio of their masses respectively is :

   1. A.$3:4$
   2. B.$4:3$
   3. C.$9:16$
   4. D.$16:9$
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   Answer: C

3. Q362023 · 13 Apr 2023 · Shift 2

   A vehicle of mass $200\text{ kg}$ is moving along a levelled curved road of radius $70\text{ m}$ with angular velocity of $0.2\text{ rad/s}$. The centripetal force acting on the vehicle is:

   1. A.$560\text{ N}$
   2. B.$14\text{ N}$
   3. C.$2800\text{ N}$
   4. D.$2240\text{ N}$
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   Answer: A

4. Q562023 · 13 Apr 2023 · Shift 2· Numerical answer

   In an experiment with sonometer when a mass of $180\text{ g}$ is attached to the string, it vibrates with fundamental frequency of $30\text{ Hz}$. When a mass $\mathrm{m}$ is attached, the string vibrates with fundamental frequency of $50\text{ Hz}$. The value of $\mathrm{m}$ is ___________ g.

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   Answer: 500

5. Q512023 · 12 Apr 2023 · Shift 1· Numerical answer

   To maintain a speed of 80 km/h by a bus of mass 500 kg on a plane rough road for 4 km distance, the work done by the engine of the bus will be ____________ kJ. [The coefficient of friction between tyre of bus and road is 0.04.]

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   Answer: 784

6. Q522023 · 11 Apr 2023 · Shift 1· Numerical answer
   
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   Answer: 300

7. Q572023 · 11 Apr 2023 · Shift 2· Numerical answer

   A block of mass $5\text{ kg}$ starting from rest is pulled up on a smooth inclined plane making an angle of $30^{\circ }$ with horizontal with an effective acceleration of $1{\text{ ms}}^{-2}$. The power delivered by the pulling force at $t=10\text{ s}$ from the start is _________ $\text{W}$. [use $g=10{\text{ ms}}^{-2}$] (calculate the nearest integer value)

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   Answer: 300

8. Q542023 · 10 Apr 2023 · Shift 1· Numerical answer
   
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   Answer: 245

9. Q552023 · 10 Apr 2023 · Shift 2· Numerical answer

   If the maximum load carried by an elevator is 1400 kg ( 600 kg - Passengers + 800 kg - elevator), which is moving up with a uniform speed of $3{\text{ m s}}^{-1}$ and the frictional force acting on it is 2000 N, then the maximum power used by the motor is _________ kW ($g=10{\text{ m/s}}^2$)

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   Answer: 48

10. Q402023 · 8 Apr 2023 · Shift 1

    At any instant the velocity of a particle of mass $500\text{ g}$ is $\left(2t\hat{i}+3t^2\hat{j}\right){\text{ms}}^{-1}$. If the force acting on the particle at $t=1\text{ s}$ is $(\hat{i}+x\hat{j})\text{N}$. Then the value of $x$ will be:

    1. A.$2$
    2. B.$4$
    3. C.$6$
    4. D.$3$
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    Answer: D

11. Q552023 · 8 Apr 2023 · Shift 1· Numerical answer

    The momentum of a body is increased by $50\%$. The percentage increase in the kinetic energy of the body is ___________ $\%$.

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    Answer: 125

12. Q352023 · 8 Apr 2023 · Shift 2

    A bullet of mass $0.1\mathrm{kg}$ moving horizontally with speed $400\mathrm{m}{\mathrm{s}}^{-1}$ hits a wooden block of mass $3.9\mathrm{kg}$ kept on a horizontal rough surface. The bullet gets embedded into the block and moves $20\mathrm{m}$ before coming to rest. The coefficient of friction between the block and the surface is ____. (Given $\mathrm{g}=10m/{\mathrm{s}}^2$ )

    1. A.$0.65$
    2. B.$0.25$
    3. C.$0.50$
    4. D.$0.90$
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    Answer: B

13. Q532023 · 8 Apr 2023 · Shift 2· Numerical answer

    A guitar string of length 90 cm vibrates with a fundamental frequency of 120 Hz. The length of the string producing a fundamental frequency of 180 Hz will be _________ cm.

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    Answer: 60

14. Q542023 · 8 Apr 2023 · Shift 2· Numerical answer

    A body of mass $5\mathrm{kg}$ is moving with a momentum of $10\mathrm{kg}\mathrm{m}{\mathrm{s}}^{-1}$. Now a force of $2\mathrm{N}$ acts on the body in the direction of its motion for $5\mathrm{s}$. The increase in the Kinetic energy of the body is ____ $\mathrm{J}$.

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    Answer: 30

15. Q442023 · 1 Feb 2023 · Shift 1

    A block of mass $5\text{ kg}$ is placed at rest on a table of rough surface. Now, if a force of $30\text{ N}$ is applied in the direction parallel to surface of the table, the block slides through a distance of $50\text{ m}$ in an interval of time $10\text{ s}$. Coefficient of kinetic friction is (given, $g=10{\text{ ms}}^{-2}$):

    1. A.0.25
    2. B.0.75
    3. C.0.60
    4. D.0.50
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    Answer: D

16. Q572023 · 1 Feb 2023 · Shift 1· Numerical answer
    
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    Answer: 2

17. Q332023 · 31 Jan 2023 · Shift 1

    Spherical insulating ball and a spherical metallic ball of same size and mass are dropped from the same height. Choose the correct statement out of the following {Assume negligible air friction}

    1. A.Metal ball will reach the earth's surface earlier than the insulating ball
    2. B.Both will reach the earth's surface simultaneously.
    3. C.Insulating ball will reach the earth's surface earlier than the metal ball
    4. D.Time taken by them to reach the earth's surface will be independent of the properties of their materials
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    Answer: C

18. Q512023 · 31 Jan 2023 · Shift 1· Numerical answer

    A lift of mass $\mathrm{M}=500\text{ kg}$ is descending with speed of $2{\text{ ms}}^{-1}$. Its supporting cable begins to slip thus allowing it to fall with a constant acceleration of $2{\text{ ms}}^{-2}$. The kinetic energy of the lift at the end of fall through to a distance of $6\text{ m}$ will be ___________ kJ.

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    Answer: 7

19. Q532023 · 31 Jan 2023 · Shift 1· Numerical answer
    
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    Answer: 20

20. Q402023 · 31 Jan 2023 · Shift 2

    A body of mass $10\text{ kg}$ is moving with an initial speed of $20\text{ m/s}$. The body stops after $5\text{ s}$ due to friction between body and the floor. The value of the coefficient of friction is: (Take acceleration due to gravity $g=10{\text{ ms}}^{-2}$ )

    1. A.$0.3$
    2. B.$0.2$
    3. C.$0.5$
    4. D.$0.4$
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    Answer: D

21. Q472023 · 31 Jan 2023 · Shift 2

    A stone of mass $1\text{ kg}$ is tied to end of a massless string of length $1\text{ m}$. If the breaking tension of the string is $400\text{ N}$, then maximum linear velocity, the stone can have without breaking the string, while rotating in horizontal plane, is :

    1. A.$20{\text{ ms}}^{-1}$
    2. B.$40{\text{ ms}}^{-1}$
    3. C.$400{\text{ ms}}^{-1}$
    4. D.$10{\text{ ms}}^{-1}$
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    Answer: A

22. Q332023 · 30 Jan 2023 · Shift 1

    A small object at rest, absorbs a light pulse of power $20\mathrm{mW}$ and duration $300\mathrm{ns}$. Assuming speed of light as $3\times 10^{8}m/s$, the momentum of the object becomes equal to :

    1. A.$1\times 10^{-17}\mathrm{kg}m/s$
    2. B.$0.5\times 10^{-17}\mathrm{kg}m/s$
    3. C.$3\times 10^{-17}\mathrm{kg}m/s$
    4. D.$2\times 10^{-17}\mathrm{kg}m/s$
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    Answer: D

23. Q372023 · 30 Jan 2023 · Shift 1
    
    1. A.$0.25m/s$
    2. B.$4m/s$
    3. C.$0$
    4. D.$2m/s$
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    Answer: D

24. Q442023 · 30 Jan 2023 · Shift 1
    
    1. A.b and c
    2. B.c and a
    3. C.a and b
    4. D.c and b
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    Answer: D

25. Q382023 · 29 Jan 2023 · Shift 1

    A block of mass $m$ slides down the plane inclined at angle $30^{\circ }$ with an acceleration $\frac{g}{4}$. The value of coefficient of kinetic friction will be:

    1. A.$\frac{2\sqrt{3}-1}{2}$
    2. B.$\frac{\sqrt{3}}{2}$
    3. C.$\frac{1}{2\sqrt{3}}$
    4. D.$\frac{2\sqrt{3}+1}{2}$
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    Answer: C