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Work Power and Energy

267 Questions Start Errorless Test
All Exams Allen Objective Errorless
JEE (Advanced) 2013 Q76 Errorless 2. 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 Q77 Errorless 4. 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
AMU (Med.) 2012 Q78 Errorless 2. 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 Q79 Errorless 2. 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 Q80 Errorless 3. 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 Q81 Errorless 3. 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 Q82 Errorless 3. 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 Q83 Errorless 3. 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 Q84 Errorless 3. 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 Q85 Errorless 4. 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 Q86 Errorless 5. 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 Q87 Errorless 5. 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.
45Ā°
C.
90Ā°
D.
180Ā°
Kerala PET 2012 Q88 Errorless 8. 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
Odisha JEE 2011, 12 Q89 Errorless 1. Work Done by Constant Force MCQ
A block of mass 5kg is resting on a smooth surface. At what angle a force of 20N be acted on the body so that it will acquired a kinetic energy of 40J after moving 4m
A.
30Ā°
B.
45Ā°
C.
60Ā°
D.
120Ā°
CBSE PMT (Pre.) 2011 Q90 Errorless 4. Power MCQ
A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest
A.
At the instant just after the body is projected
B.
At the highest position of the body
C.
At the instant just before the body hits the earth
D.
It remains constant all through
Odisha JEE 2011 Q91 Errorless 5. Elastic and Inelastic Collision MCQ
Two masses of $0.25\mathrm{kg}$ each moves towards each other with speed $3\mathrm{ms}^{-1}$ and $1\mathrm{ms}^{-1}$ collide and stick together. Find the final velocity
A.
$0.5\mathrm{ms}^{-1}$
B.
$2\mathrm{ms}^{-1}$
C.
$1\mathrm{ms}^{-1}$
D.
$0.25\mathrm{ms}^{-1}$
Kerala PET 2011 Q92 Errorless 5. Elastic and Inelastic Collision MCQ
A ball dropped from a height of 2m rebounds to a height of 1.5m after hitting the ground. Then the percentage of energy lost is
A.
25
B.
30
C.
50
D.
100
E.
200
IIT-JEE 2011 Q93 Errorless 7. Critical Thinking MCQ
A ball of mass 0.2 kg rests on a vertical post of height 5 m. A bullet of mass 0.01 kg, traveling with a velocity V m/s in a horizontal direction, hits the centre of the ball. After the collision, the ball and bullet travel independently. The ball hits the ground at a distance of 20 m and the bullet at a distance of 100 m from the foot of the post. The initial velocity V of the bullet is
A.
250m/s
B.
$250\sqrt{2}$ m/s
C.
400m/s
D.
500m/s
CBSE PMT (Pre.) 2011 Q94 Errorless 10. Self Evaluation Test MCQ
The potential energy of a system increases if work is done
A.
Upon the system by a conservative force
B.
Upon the system by a non-conservative force
C.
By the system against a conservative force
D.
By the system against a non-conservative force
Kerala PMT 2011 Q95 Errorless 10. Self Evaluation Test MCQ
Choose the incorrect statement
A.
No work is done if the displacement is perpendicular to the direction of the applied force
B.
If the angle between the force and displacement vectors is obtuse, then the work done is negative
C.
Frictional force in non-conservative
D.
All the central forces are non-conservative
E.
Kinetic energy is conserved in elastic collision
Kerala PMT 2010 Q96 Errorless 1. Work Done by Constant Force MCQ
Stopping distance of a moving vehicle is directly proportional to
A.
Square of the initial velocity
B.
Square of the initial acceleration
C.
The initial velocity
D.
The initial acceleration
E.
Mass of the vehicle
AIIMS 2010 Q97 Errorless 1. Work Done by Constant Force MCQ
A cord is used to lower vertically a block of mass $M$ by a distance $d$ with constant downward acceleration $\frac{g}{4}$ . Work done by the cord on the block is
A.
$Mg\frac{d}{4}$
B.
$3Mg\frac{d}{4}$
C.
$-3Mg\frac{d}{4}$
D.
$Mgd$
AIEEE 2010 Q98 Errorless 2. Work Done by Variable Force MCQ
The potential energy function for the force between two atoms in a diatomic molecule is approximately given by $U(x) = \frac{a}{x^{12}} - \frac{b}{x^6}$ , where $a$ and $b$ are constants and $x$ is the distance between the atoms. If the dissociation energy of the molecule is $D = [U(x = \infty) - U_{\mathrm{atequilibrium}}]$ , $D$ is
A.
$\frac{b^2}{6a}$
B.
$\frac{b^2}{2a}$
C.
$\frac{b^2}{12a}$
D.
$\frac{b^2}{4a}$
J & K CET 2010 Q99 Errorless 3. Conservation of Energy and Momentum MCQ
The energy associated with one gram of mass is
A.
$9 \times 10^{-13} J$
B.
$9 \times 10^{-16} J$
C.
$9 \times 10^{13} J$
D.
$9 \times 10^{16} J$
CBSE PMT 2010 Q100 Errorless 4. Power MCQ
An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine
A.
800 W
B.
400 W
C.
200 W
D.
100 W