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Work Power and Energy

505 Questions Start Allen Test
All Exams Allen Objective Errorless
JEE (Advanced) 2014 Q101 Errorless Graphical Questions MCQ
A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy K with time t most appropriately? The figures are only illustrative and not to the scale
A.
B.
C.
D.
MHT CET 2014 Q102 Objective Medical entrances' gallery MCQ
A string of length L and force constant k is stretched to obtain extension l. It is further stretched to obtain extension $l_{1}$ . The work done in second stretching is
A.
$\frac{1}{2}kl_{1}(2l+l_{1})$
B.
$\frac{1}{2}kl_{1}^{2}$
C.
$\frac{1}{2}k(l^{2}+l_{1}^{2})$
D.
$\frac{1}{2}k(l_{1}^{2}-l^{2})$
Uttarakhand PMT 2014 Q103 Objective Medical entrances' gallery MCQ
A body is initially at rest. It undergoes one dimensional motion with constant acceleration. The power delivered to it at time t is proportional to
A.
$t^{1/2}$
B.
t
C.
$t^{3/2}$
D.
$t^{2}$
Kerala CEE 2014 Q104 Objective Medical entrances' gallery MCQ
If two persons A and B take 2 s and 4 s respectively to lift an object to the same height h, then the ratio of their powers is
A.
1:2
B.
1:1
C.
2:1
D.
1:3
E.
3:1
Kerala CEE 2014 Q105 Objective Medical entrances' gallery MCQ
If a machine gun fires n bullets per second each with kinetic energy K, then the power of the machine gun is
A.
$nK^{2}$
B.
$\frac{K}{n}$
C.
$n^{2}K$
D.
nK
E.
$\frac{n}{K}$
NEET (Kamataka) 2013 Q106 Errorless Work Done by Variable Force MCQ
A particle with total energy E is moving in a potential energy regions $U(x)$ . Motion of the particle is restricted to the region when
A.
$U(x) < E$
B.
$U(x) = O$
C.
$U(x) \leq E$
D.
$U(x) > E$
JEE (Advanced) 2013 Q107 Errorless Work Done by Variable Force MCQ
The work done on a particle of mass m by a force, $K\left[\frac{x}{(x^{2}+y^{2})^{3/2}}\hat{i}+\frac{y}{(x^{2}+y^{2})^{3/2}}\hat{j}\right]$ (K being a constant of appropriate dimensions), when the particle is taken from the point $(a,0)$ to the point $(0,a)$ along a circular path of radius a about the origin in the x-y plane is
A.
$\frac{2K\pi}{a}$
B.
$\frac{K\pi}{a}$
C.
$\frac{K\pi}{2a}$
D.
0
WB-JEE 2013 Q108 Errorless POWER MCQ
A particle is acted upon by a constant power. Then, which of the following physical quantity remains constant
A.
Speed
B.
Rate of change of acceleration
C.
Kinetic energy
D.
Rate of change of kinetic energy
NEET 2013 Q109 Objective Medical entrances' gallery MCQ
A uniform force of $(3\hat{\mathbf{i}}+\hat{\mathbf{j}})$ N acts on a particle of mass 2 kg. Hence, the particle is displaced from position $(2\hat{\mathbf{i}}+\hat{\mathbf{k}})$ m to position $(4\hat{\mathbf{i}}+3\hat{\mathbf{j}}-\hat{\mathbf{k}})$ m. The work done by the force on the particle is
A.
9 J
B.
6 J
C.
13 J
D.
15 J
J&K CET 2013 Q110 Objective Medical entrances' gallery MCQ
The power (P) of an engine lifting a mass of 100 kg upto a height of 10 m in 1 min is
A.
163.3 W
B.
9800 W
C.
10000 W
D.
5000 W
EAMCET 2013 Q111 Objective Medical entrances' gallery MCQ
A body of mass 300 kg is moved through 10 m along a smooth inclined plane of angle $30^{\circ}$ . The work done in moving (in joules) is (Take, $g = 9.8 \, ms^{-2}$ )
A.
4900
B.
9800
C.
14700
D.
2450
EAMCET 2013 Q112 Objective Medical entrances' gallery MCQ
Force constants of two wires A and B of the same material are k and 2k, respectively. If the two wires are stretched equally, then the ratio of work done in stretching $\left(\frac{W_{A}}{W_{B}}\right)$ is
A.
$\frac{1}{3}$
B.
$\frac{1}{2}$
C.
$\frac{3}{2}$
D.
$\frac{1}{4}$
KCET 2013 Q113 Objective Medical entrances' gallery MCQ
A truck accelerates from speed v to 2v. Work done during this is
A.
three times as the work done in accelerating it from rest to v
B.
same as the work done in accelerating it from rest to v
C.
four times as the work done in accelerating it from rest to v
D.
less than the work done in accelerating it from rest to v
Kerala CET 2013 Q114 Objective Medical entrances' gallery MCQ
A block of 200 g mass is dropped from a height of 2 m on to a spring and compresses the spring to a distance of 50 cm. The force constant of the spring is
A.
$20 \, Nm^{-1}$
B.
$40 \, Nm^{-1}$
C.
$30 \, Nm^{-1}$
D.
$60 \, Nm^{-1}$
E.
$10 \, Nm^{-1}$
AMU (Med.) 2012 Q115 Errorless Work Done by Variable Force MCQ
A particle in a certain conservative force field has a potential energy given by $U = \frac{20xy}{z}$ . The force exerted on it is
A.
$\left(\frac{20y}{z}\right)\hat{i}+\left(\frac{20x}{z}\right)\hat{j}+\left(\frac{20xy}{z^{2}}\right)\hat{k}$
B.
$-\left(\frac{20y}{z}\right)\hat{i}-\left(\frac{20x}{z}\right)\hat{j}+\left(\frac{20xy}{z^{2}}\right)\hat{k}$
C.
$-\left(\frac{20y}{z}\right)\hat{i}-\left(\frac{20x}{z}\right)\hat{j}-\left(\frac{20xy}{z^{2}}\right)\hat{k}$
D.
$\left(\frac{20y}{z}\right)\hat{i}+\left(\frac{20x}{z}\right)\hat{j}-\left(\frac{20xy}{z^{2}}\right)\hat{k}$
CBSE PMT (Pre.) 2012 Q116 Errorless Work Done by Variable Force MCQ
The potential energy of a particle in a force field is $U = \frac{A}{r^{2}} - \frac{B}{r}$ , where A and B are positive constants and r is the distance of particle from the centre of the field. For stable equilibrium, the distance of the particle is
A.
B / 2A
B.
2A / B
C.
A / B
D.
B / A
WB-JEE 2012 Q117 Errorless Conservation of Energy and Momentum MCQ
A spherical ball $A$ of mass $4kg$ , moving along a straight line strikes another spherical ball $B$ of mass $1kg$ at rest. After the collision, $A$ and $B$ move with velocities $v_{1}ms^{-1}$ and $v_{2}ms^{-1}$ respectively making angles of $30^{\circ}$ and $60^{\circ}$ with respect to the original direction of motion of $A$ . The ratio $\frac{v_1}{v_2}$ will be
A.
$\sqrt{3}/4$
B.
$4/\sqrt{3}$
C.
$1/\sqrt{3}$
D.
$\sqrt{3}$
CBSE PMT (Pre.) 2012 Q118 Errorless Conservation of Energy and Momentum MCQ
Two spheres $A$ and $B$ of masses $m_{1}$ and $m_{2}$ respectively collide. $A$ is at rest initially and $B$ is moving with velocity $v$ along $x$ -axis. After collision $B$ has a velocity $\frac{v}{2}$ in a direction perpendicular to the original direction. The mass $A$ moves after collision in the direction
A.
Same as that of $B$
B.
Opposite to that of $B$
C.
$\theta = \tan^{-1}(1/2)$ to the $x$ -axis
D.
$\theta = \tan^{-1}(-1/2)$ to the $x$ -axis
Kerala PET 2012 Q119 Errorless Conservation of Energy and Momentum MCQ
A girl in a swing is 2.5m above ground at the maximum height and at 1.5m above the ground at the lowest point. Her maximum velocity in the swing is $(g = 10 \, ms^{-2})$
A.
$5\sqrt{2} \, ms^{-1}$
B.
$2\sqrt{5} \, ms^{-1}$
C.
$2\sqrt{3} \, ms^{-1}$
D.
$3\sqrt{2} \, ms^{-1}$
E.
$4\sqrt{2} \, ms^{-1}$
CBSE PMT (Mains) 2012 Q120 Errorless Conservation of Energy and Momentum MCQ
A stone is dropped from a height h. It hits the ground with a certain momentum P. If the same stone is dropped from a height 100% more than the previous height, the momentum when it hits the ground will change by
A.
68%
B.
41%
C.
200%
D.
100%
MP PET 2012 Q121 Errorless Conservation of Energy and Momentum MCQ
A particle of mass 4m which is at rest explodes into three fragments. Two of the fragments each of mass m are found to move with a speed 'v' each in mutually perpendicular directions. The total energy released in this process
A.
0
B.
$\frac{3}{2}mv^{2}$
C.
$\frac{1}{2}mv^{2}$
D.
$2mv^{2}$
CBSE PMT (Mains) 2012 Q122 Errorless POWER MCQ
A car of mass m starts from rest and accelerates so that instantaneous power delivered to the car has a constant magnitude $P_{0}$ . The instantaneous velocity of this car is proportional to
A.
$t^{2}P_{0}$
B.
$t^{1/2}$
C.
$t^{-1/2}$
D.
$\frac{t}{\sqrt{m}}$
Kerala PMT 2012 Q123 Errorless Elastic and Inelastic Collision MCQ
When two spheres of equal masses undergo glancing elastic collision with one of them at rest, after collision they will move
A.
Opposite to one another
B.
In the same direction
C.
Together
D.
At right angle to each other
E.
Randomly
AMU (Med.) 2012 Q124 Errorless Elastic and Inelastic Collision MCQ
A sphere P of mass m and velocity $\vec{v}_{i}$ undergoes an oblique and perfectly elastic collision with an identical sphere Q initially at rest. The angle $\theta$ between the velocities of the spheres after the collision shall be
A.
0
B.
45°
C.
90°
D.
180°
Kerala PET 2012 Q125 Errorless Graphical Questions MCQ
The shape of the curve representing the relation between the speed and kinetic energy of a moving object is
A.
Parabola
B.
Ellipse
C.
Straight line with positive slope
D.
Straight line with negative slope
E.
Exponential