Work, Energy & Power · JEE Main previous year questions

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2022 17 questions

Q352022 · 29 Jul 2022 · Shift 1
A ball is projected with kinetic energy E, at an angle of $6 0^{\circ}$ to the horizontal. The kinetic energy of this ball at the highest point of its flight will become :
1. A.Zero
2. B. $\frac{E}{2}$
3. C. $\frac{E}{4}$
4. D. $E$
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Answer: C
Q462022 · 29 Jul 2022 · Shift 1
The kinetic energy of emitted electron is $E$ when the light incident on the metal has wavelength $λ$ . To double the kinetic energy, the incident light must have wavelength:
1. A. $\frac{hc}{E λ - hc}$
2. B. $\frac{hc λ}{E λ + hc}$
3. C. $\frac{h λ}{E λ + hc}$
4. D. $\frac{hc λ}{E λ - hc}$
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Answer: B
Q412022 · 29 Jul 2022 · Shift 2
An object of mass $1 kg$ is taken to a height from the surface of earth which is equal to three times the radius of earth. The gain in potential energy of the object will be [If, $g = 10 m s^{- 2}$ and radius of earth $= 6400 km$ ]
1. A. $48 MJ$
2. B. $24 MJ$
3. C. $36 MJ$
4. D. $12 MJ$
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Answer: A
Q562022 · 28 Jul 2022 · Shift 1· Numerical answer
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Answer: 24
Q352022 · 28 Jul 2022 · Shift 2
1. A. $45 m$
2. B. $90 m$
3. C. $125 m$
4. D. $25 m$
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Answer: A
Q322022 · 27 Jul 2022 · Shift 1
1. A.
2. B.
3. C.
4. D.
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Answer: A
Q352022 · 27 Jul 2022 · Shift 1
Two cylindrical vessels of equal cross-sectional area $16 cm^{2}$ contain water upto heights $100 cm$ and $150 cm$ respectively. The vessels are interconnected so that the water levels in them become equal. The work done by the force of gravity during the process, is [Take, density of water $= 1 0^{3} kg/m^{3}$ and $g = 10 ms^{- 2}$ ] :
1. A. $0.25 J$
2. B. $1 J$
3. C. $8 J$
4. D. $12 J$
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Answer: B
Q422022 · 26 Jul 2022 · Shift 1
A monoatomic gas at pressure $P$ and volume $V$ is suddenly compressed to one eighth of its original volume. The final pressure at constant entropy will be :
1. A. $P$
2. B. $8 P$
3. C. $32 P$
4. D. $64 P$
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Answer: C
Q452022 · 26 Jul 2022 · Shift 1
1. A. $\frac{v}{2 2}$
2. B. $\frac{v}{2}$
3. C. $\frac{v}{4}$
4. D. $\frac{v}{2}$
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Answer: B
Q442022 · 25 Jul 2022 · Shift 2
A bag of sand of mass $9.8 kg$ is suspended by a rope. A bullet of $200 g$ travelling with speed $10 ms^{- 1}$ gets embedded in it, then loss of kinetic energy will be :
1. A. $4.9 J$
2. B. $9.8 J$
3. C. $14.7 J$
4. D. $19.6 J$
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Answer: B
Q482022 · 30 Jun 2022 · Shift 1
A cyclotron is working at a frequency of $10 MHz$ . If the radius of its dees is $60 cm$ . The maximum kinetic energy of accelerated proton will be : (Take : $e = 1.6 \times 1 0^{- 19} C$ , $m_{p} = 1.67 \times 1 0^{- 27} kg$ )
1. A. $7.4 MeV$
2. B. $14.86 MeV$
3. C. $7.4 GeV$
4. D. $704 GeV$
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Answer: A
Q542022 · 30 Jun 2022 · Shift 1· Numerical answer
Eight similar drops of mercury are maintained at 12 V each. All these spherical drops combine into a single big drop. The potential energy of bigger drop will be ____________ E. Where E is the potential energy of a single smaller drop.
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Answer: 32
Q382022 · 27 Jun 2022 · Shift 1
What percentage of kinetic energy of a moving particle is transferred to a stationary particle when it strikes the stationary particle of 5 times its mass? (Assume the collision to be head-on elastic collision)
1. A.50.0%
2. B.66.6%
3. C.55.6%
4. D.33.3%
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Answer: C
Q332022 · 26 Jun 2022 · Shift 2
1. A. $W_{3} > W_{2} > W_{1} > W_{4}$
2. B. $W_{3} > W_{2} > W_{4} > W_{1}$
3. C. $W_{2} > W_{3} > W_{4} > W_{1}$
4. D. $W_{2} > W_{3} > W_{1} > W_{4}$
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Answer: A
Q372022 · 26 Jun 2022 · Shift 2
A flask contains argon and oxygen in the ratio of 3 : 2 in mass and the mixture is kept at $2 7^{\circ} C$ . The ratio of their average kinetic energy per molecule respectively will be :
1. A.3 : 2
2. B.9 : 4
3. C.2 : 3
4. D.1 : 1
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Answer: D
Q522022 · 25 Jun 2022 · Shift 1· Numerical answer
A $0.5 kg$ block moving at a speed of $12 ms^{- 1}$ compresses a spring through a distance $30 cm$ when its speed is halved. The spring constant of the spring will be $Nm^{- 1}$ .
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Answer: 600
Q402022 · 24 Jun 2022 · Shift 2
Potential energy as a function of r is given by $U = \frac{A}{r ^{10}} - \frac{B}{r ^{5}}$ , where r is the interatomic distance, A and B are positive constants. The equilibrium distance between the two atoms will be :
1. A. $(\frac{A}{B})^{\frac{1}{5}}$
2. B. $(\frac{B}{A})^{\frac{1}{5}}$
3. C. $(\frac{2 A}{B})^{\frac{1}{5}}$
4. D. $(\frac{B}{2 A})^{\frac{1}{5}}$
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Answer: C