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Work Power and Energy

267 Questions Start Errorless Test
All Exams Allen Objective Errorless
NEET 2024 Q1 Errorless 7. Critical Thinking MCQ
At any instant of time t, the displacement of any particle is given by 2t-1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit)
A.
10
B.
5
C.
7
D.
6
NEET 2024 Q2 Errorless 7. Critical Thinking MCQ
Two bodies A and B of same mass undergo completely inelastic one dimensional collision. The body A moves with velocity $v_{1}$ while body B is at rest before collision. The velocity of the system after collision is $v_{2}$ . The ratio $v_{1}:v_{2}$ is
A.
1:2
B.
2:1
C.
4:1
D.
1:4
JEE (Main) 2023 Q3 Errorless 7. Critical Thinking MCQ
As per the given figure, a small ball P slides down the quadrant of a circle and hits the other ball Q of equal mass which is initially at rest. Neglecting the effect of friction and assume the collision to be elastic, the velocity of ball Q after collision will be $(g=10m/s^{2})$
A.
0
B.
$0.2 5 m / s$
C.
$2 m / s$
D.
4 m/s
JEE (Main) 2023 Q4 Errorless 7. Critical Thinking MCQ
Identify the correct statements from the following
(A) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket is negative.
(B) Work done by gravitational force in lifting a bucket out of a well by a rope tied to the bucket is negative.
(C) Work done by friction on a body sliding down an inclined plane is positive.
(D) Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity is zero.
(E) Work done by the air resistance on an oscillating pendulum is negative.
Choose the correct answer from the options given below
A.
B and E only
B.
A and C only
C.
B, D and E only
D.
B and D only
NEET 2023 Q5 Errorless 7. Critical Thinking MCQ
The potential energy of a long spring when stretched by 2cm is U. If the spring is stretched by 8cm, potential energy stored in it will be
A.
4U
B.
8U
C.
16U
D.
2U
JEE (Main) 2022 Q6 Errorless 7. Critical Thinking MCQ
A particle experiences a variable force $\vec{F} = (4x\hat{i} + 3y^2\hat{j})$ in a horizontal $x - y$ plane. Assume distance in meters and force is newton. If the particle moves from point (1, 2) to point (2, 3) in the $x - y$ plane, the kinetic energy changes by
A.
$50.0J$
B.
$12.5J$
C.
$25.0J$
D.
$0J$
JEE (Main) 2022 Q7 Errorless 7. Critical Thinking MCQ
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
A.
$\left(\frac{A}{B}\right)^{\frac{1}{5}}$
B.
$\left(\frac{B}{A}\right)^{\frac{1}{5}}$
C.
$\left(\frac{2A}{B}\right)^{\frac{1}{5}}$
D.
$\left(\frac{B}{2A}\right)^{\frac{1}{5}}$
JEE (Main) 2022 Q8 Errorless 7. Critical Thinking MCQ
A particle of mass 500 gm is moving in a straight line with velocity $v = bx^{5/2}$ . The work done by the net force during its displacement from x = 0 to x = 4m is (Take $b = 0.25 m^{-3/2} s^{-1}$ )
A.
2 J
B.
4 J
C.
8 J
D.
16 J
JEE (Main) 2022 Q9 Errorless 7. Critical Thinking MCQ
A particle of mass m is moving in a circular path of constant radius r such that its centripetal acceleration (a) is varying with time t as $a = k^{2}rt^{2}$ . Where k is a constant. The power delivered to the particle by the force acting on it is given as
A.
Zero
B.
$mk^{2}r^{2}t^{2}$
C.
$mk^{2}r^{2}t$
D.
$mk^{2}rt$
JEE (Main) 2022 Q10 Errorless 7. Critical Thinking MCQ
A body of mass 0.5 kg travels on straight line path with velocity $v = (3x^{2} + 4)m/s$ . The net workdone by the force during its displacement from x = 0 to x = 2m is
A.
64 J
B.
60 J
C.
120 J
D.
128 J
JEE (Main) 2022 Q11 Errorless 7. Critical Thinking MCQ
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
A.
4.9 J
B.
9.8 J
C.
14.7 J
D.
19.6 J
JEE (Main) 2022 Q12 Errorless 7. Critical Thinking MCQ
A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be
A.
1:1
B.
2:1
C.
1:4
D.
4:1
JEE (Main) 2022 Q13 Errorless 7. Critical Thinking MCQ
If momentum of a body is increased by 20%, then its kinetic energy increases by
A.
36%
B.
40%
C.
44%
D.
48%
JEE (Main) 2022 Q14 Errorless 7. Critical Thinking MCQ
Sand is being dropped from a stationary dropper at a rate of $0.5 \, kgs^{-1}$ on a conveyor belt moving with a velocity of $5 \, ms^{-1}$ . The power needed to keep belt moving with the same velocity will be
A.
1.25 W
B.
2.5 W
C.
6.25 W
D.
12.5 W
NEET 2022 Q15 Errorless 7. Critical Thinking MCQ
The energy that will be ideally radiated by a 100 kW transmitter in 1 hour is
A.
$36 \times 10^{5} J$
B.
$1 \times 10^{5} J$
C.
$36 \times 10^{7} J$
D.
$36 \times 10^{4} J$
NEET 2022 Q16 Errorless 7. Critical Thinking MCQ
An electric lift with a maximum load of 2000 kg (lift+passengers) is moving up with a constant speed of $1.5 \, ms^{-1}$ . The frictional force opposing the motion is 3000 N. The minimum power delivered by the motor to the lift in watts is $(g = 10 \, ms^{-2})$
A.
34500
B.
23500
C.
23000
D.
20000
JEE (Main) 2021 Q17 Errorless 7. Critical Thinking MCQ
An object of mass $m_{1}$ collides with another object of mass $m_{2}$ , which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses $m_{2}:m_{1}$ is
A.
3:1
B.
2:1
C.
1:2
D.
1:1
JEE (Main) 2021 Q18 Errorless 7. Critical Thinking MCQ
A large block of wood of mass $M = 5.99 \, \text{kg}$ is hanging from two long massless cords. A bullet of mass $m = 10 \, \text{g}$ is fired into the block and gets embedded in it. The (block + bullet) then swing upwards, their centre of mass rising a vertical distance $h = 9.8 \, \text{cm}$ before the (block + bullet) pendulum comes momentarily to rest at the end of its arc. The speed of the bullet just before collision is (Take $g = 9.8 \, \text{ms}^{-2}$ )
A.
841.4 m/s
B.
811.4 m/s
C.
831.4 m/s
D.
821.4 m/s
JEE (Main) 2021 Q19 Errorless 7. Critical Thinking MCQ
A boy is rolling a 0.5 kg ball on the frictionless floor with the speed of $20 \, ms^{-1}$ . The ball gets deflected by an obstacle on the way. After deflection it moves with 5% of its initial kinetic energy. What is the speed of the ball now
A.
$19.0 \, ms^{-1}$
B.
$4.47 \, ms^{-1}$
C.
$14.41 \, ms^{-1}$
D.
$1.00 \, ms^{-1}$
JEE (Main) 2021 Q20 Errorless 7. Critical Thinking MCQ
A porter lifts a heavy suitcase of mass $80\mathrm{kg}$ and at the destination lowers it down by a distance of $80~cm$ with a constant velocity. Calculate the workdone by the porter in lowering the suitcase (take $g = 9.8ms^{-2}$ )
A.
$-62720.0J$
B.
$-627.2J$
C.
$+627.2J$
D.
$784.0J$
JEE (Main) 2021 Q21 Errorless 7. Critical Thinking MCQ
Three objects A, B and C are kept in a straight line on a frictionless horizontal surface. The masses of A, B and C are m, 2 m and 2 m respectively. A moves towards B with a speed of 9 m/s and makes an elastic collision with it. Thereafter B makes a completely inelastic collision with C. All motions occur along same straight line. The final speed of C is
A.
$6m / s$
B.
$9m / s$
C.
$4m / s$
D.
$3m / s$
JEE (Main) 2021 Q22 Errorless 7. Critical Thinking MCQ
An automobile of mass 'm' accelerates starting from origin and initially at rest, while the engine supplies constant power P. The position is given as a function of time by
A.
$\left(\frac{9P}{8m}\right)^{\frac{1}{2}}t^{\frac{3}{2}}$
B.
$\left(\frac{8P}{9m}\right)^{\frac{1}{2}}t^{\frac{2}{3}}$
C.
$\left(\frac{9m}{8P}\right)^{\frac{1}{2}}t^{\frac{3}{2}}$
D.
$\left(\frac{8P}{9m}\right)^{\frac{1}{2}}t^{\frac{3}{2}}$
JEE (Main) 2021 Q23 Errorless 7. Critical Thinking MCQ
A body of mass 'm' dropped from a height 'h' reaches the ground with a speed of $0.8\sqrt{gh}$ . The value of work done by the air ā€“ friction is
A.
-0.68 mgh
B.
0.64 mgh
C.
mgh
D.
1.64 mgh
JEE (Main) 2021 Q24 Errorless 7. Critical Thinking MCQ
A block moving horizontally on a smooth surface with a speed of 40 m/s splits into two parts with masses in the ratio of 1:2. If the smaller part moves at 60 m/s in the same direction, then the fractional change in kinetic energy is
A.
$\frac{1}{8}$
B.
$\frac{2}{3}$
C.
$\frac{1}{3}$
D.
$\frac{1}{4}$
JEE (Main) 2020 Q25 Errorless 7. Critical Thinking MCQ
A 60 HP electric motor lifts an elevator having a maximum total load capacity of 2000 kg. If the frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to $(1\ \text{HP} = 746\ \text{W}, g = 10\ \text{ms}^{-2})$
A.
$1.7\ ms^{-1}$
B.
$2.0\ ms^{-1}$
C.
$1.9\ ms^{-1}$
D.
$1.5\ ms^{-1}$