CBSE Questions for Class 11 Medical Physics Work, Energy And Power Quiz 11 - MCQExams.com

A car is accelerated on a leveled road and attains a velocity $$4$$ times its initial velocity. In this process, the potential energy of the car:
  • Does not change
  • Becomes twice to that of initial
  • Becomes $$4$$ times that of initial
  • Becomes $$16$$ times that of initial
N identical balls are placed on a smooth horizontal surface. Another ball of same mass collides elastically with velocity $$u$$ with first ball of N balls. A process of collision is thus started in which first ball collides with second ball and the second ball with the third ball and so on. The coefficient of resulting for each collision is $$e$$. Find speed of Nth ball :
  • $$(1+e)^{N}u$$
  • $$u(1+e)^{N-1}$$
  • $$\cfrac{u(1+e)^{N-1}}{2^{N-1}}$$
  • $$u^{N}(1+e)^{N-1}$$
When a boy triples his speed, his kinetic energy becomes 
  • half
  • double
  • nine times
  • no charge
The energy stored in water of a dam is the kinetic energy.
  • True
  • False
A position dependent force $$ F = 7 - 2x + 3x^2 $$ newton acts on a small body of mass $$2 $$ kg displace it from $$ x = 0$$ to $$ x = 5 m $$ the work done in joules is 
  • $$ 70 $$
  • $$ 270 $$
  • $$ 35 $$
  • $$ 135 $$
If the stone is thrown up vertically and return to ground, its potential energy is maximum 
  • During the upward journey
  • At the maximum height
  • During the return journey
  • At the bottom
A particle moves under the effect of a force $$ F =Cx $$ from $$ x = 0 $$ to $$ x =x_1 $$ The work done process is 
  • $$ Cx^2_1 $$
  • $$ \frac {1}{2} Cx^2_1 $$
  • $$ Cx_1 $$
  • $$ Zero $$
If velocity of a body is twice of previous velocity, then kinetic energy will become
  • $$ 2 $$ times
  • $$ \frac{1}{2} $$ times
  • $$ 4 $$ times
  • $$ 1$$ times
An object of $$m\ kg$$ with speed of $$v\ m/s$$ strikes a wall at an angle $$\theta$$ and rebounds at the same speed and same angle. The magnitude of the change in momentum of the object will be 
1811789_ab2c958c53754ff1ab1c691e9559c24d.png
  • $$2mv\cos \theta $$
  • $$2mv\sin \theta $$
  • $$0$$
  • $$2\ mv$$
The decrease in the potential energy of a ball of mass $$ 20 kg $$ which falls from a height of $$ 50 cm  $$ is  
  • $$ 968 J $$
  • $$ 98 J $$
  • $$ 1980 J$$
  • None of these
A body is moved along a straight line by a machine delivering  constant power. The distance moved by the body in time $$ t $$ is proportional to
  • $$ t^{1/2} $$
  • $$ t^{3/4} $$
  • $$ t^{3/2} $$
  • $$ t^2 $$
The relation between the displacement $$ X $$ of an object produced by the application of the variable force $$ F $$ is represented by a graph shown in the figure. If the object undergoes a displacement from $$ X=0.5m $$ to $$ X=2.5m $$ the work done will be approximately equal to 
1812985_b03f43165ecd474e8c0bead96a7b52a5.png
  • $$ 16 J $$
  • $$ 32 J $$
  • $$ 1.6 J $$
  • $$ 8 J $$
The displacement x of a particle moving in one dimension under the action of a constant force is related to the time t by the equation $$ t = \sqrt { x} +3 $$ where x is in meters and t is in seconds . the work done by the force in the first $$ 6 $$ second is
  • $$ 9 J $$
  • $$ 6 J $$
  • $$ 0 J $$
  • $$ 3 J $$
The force constant of a wire is k and that of another wire is $$2k $$When both the wires are stretched through same distance, then the work done.
  • $$W_2 = 2W^2_1 $$
  • $$ W_2 =2W_1 $$
  • $$ W_2 =W_1 $$
  • $$ W_2 = 0.5 W_1 $$
A body of mass$$  3 $$kg is under a force, which causes a displacement  in it is given by $$ S = \frac {t^3}{3}  ( in m ) $$ find the work done by the force in first $$ 2 $$ seconds
  • $$ 2 J $$
  • $$ 3.8 J $$
  • $$ 5.2 J $$
  • $$ 24 J $$
The spring will have maximum potential energy when 
  • it is pulled out
  • it is compressed
  • both (a) and (b)
  • neither (a) nor (b)
Work done on a body is equal to change in .......
  • only Kinetic energy
  • only potential energy
  • only mechanical energy
  • energy
Masses of two bodies are $$1$$ kg and $$4$$ kg respectively. If their kinetic energies are in $$2:1$$ proportion, the ratio of their speeds is .........
  • $$2\sqrt{2}:1$$
  • $$1:\sqrt{2}$$
  • $$1:2$$
  • $$2:1$$
A $$5-kg$$ cart moving to the right with a speed of $$6\ m/s$$ collides with a concrete wall and rebounds with a speed of $$2\ m/s$$. What is the change in momentum of the cart?
  • $$0$$
  • $$40\ kg.m/s$$
  • $$-40\ kg.m/s$$
  • $$-30\ kg.m/s$$
  • $$-10\ kg.m/s$$
In one experiment, two balls of clay of the same mass travel with the same speed v toward each other. They collide head-on and come to rest. In a second experiment, two clay balls of the same mass are again used. One ball hangs at rest, suspended from the ceiling by a thread. The second ball is fired toward the first at speed v, to collide, stick to the first ball, and continue to move forward. Is the kinetic energy that is transformed into internal energy in the first experiment:
  • one-fourth as much as in the second experiment,
  • one-half as much as in the second experiment,
  • the same as in the second experiment,
  • twice as much as in the second experiment, or
  • four times as much as in the second experiment.
A pile driver drives postes into the ground by repeatedly dropping a heavy object on them. Assume the object is dropped from the same height each time. By what factor does the energy of the pile driver-Earth system change when the mass of the object being dropped is doubled?
  • $$\dfrac{1}{2}$$
  • $$1$$; the energy is the sane
  • $$2$$
  • $$4$$
A $$10.0-g$$ bullet is fired into a $$200-g$$ block of wood at rest on a horizontal surface. After impact, the block slides $$8.00\ m$$ before coming to rest. If the coefficient of friction between the block and the bullet before impact?
  • $$106\ m/s$$
  • $$166\ m/s$$
  • $$226\ m/s$$
  • $$286\ m/s$$
  • none of those answer is correct
Calculate the energy possessed by a stone of mass $$10\ kg$$ kept at a height of $$5\ m$$. 
Take $$g = 9.8\ m/s^{2}$$
  • $$196\ J $$
  • $$49\ J $$
  • $$490\ J $$
  • $$980\ J $$
A bar of mass $$M$$ and length $$L$$ is in pure translatory motion and its centre of mass has velocity $$V$$. It collides and sticks to a second identical bar which is initially at rest. (Assume that it becomes one composite bar of length $$2L$$). The angular velocity of the composite bar after collision will be :

73047.jpg
  • $$\dfrac{3}{4}\dfrac{V}{L}$$
  • $$\dfrac{4}{3}\dfrac{V}{L}$$
  • Counterclockwise
  • Clockwise
The work done by the force $$\vec{F}=A(y^{2}\hat{i}+2x^{2}\hat{j})$$, where $$A$$ is a constant and $$x$$ & $$y$$ are in meters around the path shown is :

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  • $$zero$$
  • $$Ad$$
  • $$Ad^{2}$$
  • $$Ad^{3}$$
A particle of mass $$m$$ is moving with speed $$u$$. It is stopped by a force $$F$$ in distance $$x$$ . If the stopping force is $$4F$$ then 
  • work done by stopping force in second case will be same as that in first case
  • work done by stopping force in second case will be $$2$$ times of that in first case
  • work done by stopping force in second case will be $$\dfrac{1}{2}$$ of that in first case
  • work done by stopping force in second case will be $$\dfrac{1}{4}$$ of that in first case
A ball of mass m moves towards a moving wall of infinite mass with a speed 'v' along the normal to the wall. The speed of the wall is 'u' toward the ball. The speed of the ball after elastic collision with wall is
  • $$u + v$$ away from the wall
  • $$2u + v$$ away from the wall
  • $$|u - v|$$ away from the wall
  • $$|v- 2u |$$ away from the wall
A force $$\vec{F}=(3t\hat{i}+5\hat{j})$$ N acts on a particle whose position vector varies as $$\vec{S}=(2t^{2}\hat{i}+5\hat{j})$$ m, where $$t$$ is time in seconds. The work done by this force from $$t=0$$ to $$t=2s$$ is:
  • 23 J
  • 32 J
  • zero
  • can't be obtained
A uniform bar of mass $$M$$ and length $$L$$ collides with a horizontal surface. Before collision, velocity of centre of mass was $$v_{0}$$ and no angular velocity. Just after collision, velocity of centre of mass of bar becomes $$v$$ in upward direction as shown. Angular velocity $$\omega $$ of the bar just after impact is:

73048.jpg
  • $$\dfrac{3\left ( v_{0}+v \right )cos\theta }{2L}$$
  • $$\dfrac{6\left ( v_{0}-v \right )cos\theta }{L}$$
  • $$\dfrac{\left ( v_{0}+v \right )cos\theta }{L}$$
  • $$\dfrac{\left ( v_{0}-v \right )cos\theta }{6L}$$
A particle of mass $$m_0,$$ travelling at speed $$v_0,$$ strikes a stationary particle of mass $$2m_0.$$ As a result, the particle of mass $$m_0$$ is deflected through $$45^o$$ and has a final speed of $$\dfrac{v_0}{\sqrt2}$$. Then the speed of the particle of mass $$2m_0$$ after this collision is 
  • $$\dfrac{v_0}{2}$$
  • $$\dfrac{v_0}{2\sqrt2}$$
  • $$\sqrt2v_0$$
  • $$\dfrac{v_0}{\sqrt2}$$
A particle of mass $$m$$ moves along the quarter section of the circular path whose centre is at the origin. The radius of the circular path is $$a$$. A force $$\vec{F}=y\hat{i}-x\hat{j}$$ newton acts on the particle, where $$x, y$$ denote the coordinates of position of the particle. The work done by this force in taking the particle from point A ($$a, 0$$) to point B ($$0, a$$) along the circular path is

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  • $$\dfrac{\pi a^{2}}{4}J$$
  • $$\dfrac{\pi a^{2}}{2}J$$
  • $$\dfrac{\pi a^{2}}{3}J$$
  • $$None\ of\ these$$
A force $$\vec F=(3t\hat i+5\hat j)$$N acts on a body due to which its displacement varies as $$\vec S=(2t^2\hat i-5\hat j)m$$. Work done by this force in $$2$$ second is
  • 32 J
  • 24 J
  • 46 J
  • 20 J
The world class Moses Mabhida football stadium situated in Durban has a symmetrical arc of length 350 m and a height of 106 m, as shown in the picture below on the left.
The picture on the right shows a funicular (Skycar), which takes tourists to the top of the arc. Suppose that the Skycar with tourists inside, starts from the base of the arc and travels a distance of 175 m along the arc to the viewing platform at the top. Assume that the work done by friction during the Skycars complete ascent is $$5.8\times 10^5J$$. If the combined mass of the Skycar and tourists is 5000 kg, then the work done by the motor that lifts the Skycar is approximately equal to,
78924.png
  • $$4.6\times 10^6 J$$
  • $$5.8\times 10^6 J$$
  • $$8.0\times 10^6 J$$
  • $$9.2\times 10^6 J$$
In using an axe to split firewood, the following energy forms are involved

(i) Chemical (muscle) energy
(ii) Mechanical potential energy of the axe;
(iii) Chemical (binding) energy of wood, heat energy, sound energy and kinetic
energy of wood fragments;
(iv) Mechanical kinetic energy of the axe.
Which is the most likely sequence of the energy exchanges?
  • (i), (ii), (iv), (iii)
  • (i), (iv), (iii), (ii)
  • (iv), (i), (ii), (iii)
  • (i), (ii), (iii), (iv)
The figure shows a block having a small basket in it and an small inclined plane (with fixed angle) is rigidly attached to the block. The combined mass (including incline plane) of all these is M = 5 kg. Initially they are at rest. Now identical balls each of mass m=1 kg are thrown horizontally with velocity v = 5m/s (with respect to ground) which strike the inclined plane and then are collected in the small basket. Assume that in the basket balls come to rest with respect to basket. Choose the correct statement(s) from the following : 

75357.png
  • After collecting 5 balls the speed of the block will be 2.5 m/s
  • After collecting 10 balls the speed of the block will be (10/3) m/s
  • The velocity of the block will never be exactly 5 m/s no matter how many balls are collected in the basket.
  • Increase in speed of the block will be same every time for collection of each ball in the basket
A bullet moving with a speed of $$100\; ms^{-1}$$ can just penetrate into two planks of equal thickness. Then, the number of such planks the bullet will penetrate, if speed is doubled will be
  • 6
  • 20
  • 4
  • 8
A block of mass $$10kg$$ is released on a fixed wedge inside a cart which is moved with constant velocity $$10 \ ms^{-1}$$ towards right. There is no relative motion between block and cart. Then work done by normal reaction on block in two seconds from ground frame will be $$(g=10 \ ms^{-2})$$:
117433.jpg
  • $$1320 J$$
  • $$960 J$$
  • $$1200 J$$
  • $$240 J$$
A particle of mass m, moving with velocity v collides a stationary particles of mass 2m. As a result of collision, the particle of mass m deviates by $$45^o$$ and has final speed of $$\dfrac {v}{2}$$. For this situation mark out the correct statement (s).
  • The angle of divergence between particles after collision is $$\dfrac {\pi}{2}$$
  • The angle of divergence between particles after collision is less than $$\dfrac {\pi}{2}$$
  • Collision is elastic
  • Collision is inelastic
Sunil rolls a marble ball down a frictionless inclined plane as shown above. What kind of energies are possessed by the rolling marble ball?

85200_9f941723bcc140f88767f1935dfbfba4.png
  • (i) and (ii) only
  • (ii) and (iii) only
  • (iii) and (i) only
  • (i), (ii) and (iii)
The force exerted by a compression device is given by $$ F(x) = kx (x-l)$$  for $$ 0 \leq  x \leq  l$$, where $$l$$ is the maximum possible compression, $$x$$ is the compression  and $$k$$ is the constant. Work done to compress the device by a distance $$d$$ will be maximum when 
  • $$d = \dfrac {l}{4}$$
  • $$d = \dfrac {l}{\sqrt{2}}$$
  • $$d = \dfrac {l}{2}$$
  • $$d = l $$
The relationship between the force $$F$$ and position $$x$$ of a body is as shown in figure. The work done by force $$F$$, in displacing the body from $$x=1 \ m$$ to $$x=5 \ m$$ will be
117331.png
  • 30 J
  • 15 J
  • 25 J
  • 20 J
A uniform solid sphere of radius $$r$$ is rolling on a smooth horizontal surface with velocity $$V$$ and angular velocity $$\omega$$  (where $$V=\omega r)$$. The sphere collides with a sharp edge on the wall as shown in the figure. The coefficient of friction between the sphere and the edge $$\mu=1/5$$. Just after the collision the angular velocity of the sphere becomes equal to zero. The linear velocity of the sphere just after the collision is equal to :
120430_f33bad3a676e4b72aa5a9f2f2cc41811.png
  • $$V$$
  • $$\dfrac {V}{5}$$
  • $$\dfrac {3V}{5}$$
  • $$\dfrac {V}{6}$$
A mass $${ m }_{ 1 }$$ with initial speed $${ v }_{ 0 }$$ in the positive $$x$$-direction collides with a mass $${ m }_{ 2 }=2{ m }_{ 1 }$$ which is initially at rest at the origin, as shown in figure. After the collision $${ m }_{ 1 }$$ moves off with speed $${ v }_{ 1 }={ v }_{ 0 }/2$$ in the negative $$y$$- direction, and $${ m }_{ 2 }$$ moves off with speed $${ v }_{ 2 }$$ at angle $$\theta$$. Find the velocity (magnitude and direction) of the centre of mass after the collision :

133472_e5427870fd9c44bb8219995507be0d06.png
  • $${ v }_{ 0 }/3$$
  • $${ v }_{ 0 }/2$$
  • $${ v }_{ 0 }/5$$
  • $${ v }_{ 0 }/6$$
A body of mass $$m$$ is hauled from the Earth's surface by applying a force $$\vec{F}$$ varying with the height of ascent $$y$$ as $$\vec{F}=2(ay-1)mg$$, where $$a$$ is a positive constant. Find the work performed by this force $$W$$ and the increment in the body's potential energy $$\Delta U$$ in the gravitational field of the Earth over the first half of the ascent.
  • $$\displaystyle W=\frac{3mg}{4a}$$, $$\displaystyle\Delta U=\frac{mg}{2a}$$
  • $$\displaystyle W=\frac{3mg}{a}$$, $$\displaystyle\Delta U=\frac{mg}{2a}$$
  • $$\displaystyle W=\frac{3mg}{4a}$$, $$\displaystyle\Delta U=\frac{mg}{a}$$
  • $$\displaystyle W=\frac{3mg}{4a}$$, $$\displaystyle\Delta U=\frac{mg}{3a}$$
A force $$F = - K (y  \widehat i + x  \widehat j)$$ (where $$K$$ is positive constant) acts on a particle moving in the $$x-y$$ plane. Starting from the origin, the particle is taken along the $$x$$-axis to the point $$(a, 0)$$ and then parallel to $$y$$-axis to the point $$(0, a)$$. The total work done by the force $$F$$ on the particle is:
  • $$- 2 Ka^2$$
  • $$2 Ka^2$$
  • $$- Ka^2$$
  • $$Ka^2$$
A force $$F = - K (y  \widehat i + x  \widehat j)$$, (where $$K$$ is a +ve constant) acts on a particle moving in xy plane starting from origin, the particle is taken along the positive x-axis to the point ($$a, 0$$) and then parallel to y axis to the point ($$a, a$$). The total work done by force $$F$$ on the particle is
  • $$- 2 Ka^2$$
  • $$2 Ka^2$$
  • $$- Ka^2$$
  • $$ Ka^2$$
How soon will the frame come to the orientation shown in figure (b) after collision?

161158.PNG
  • $$\cfrac { \pi l }{ 4v } $$
  • $$\cfrac {7 \pi l }{ 8v } $$
  • $$\cfrac { \pi l }{ v } $$
  • $$\cfrac { 7\pi l }{ 4v } $$
A solid sphere rolls without slipping on a rough horizontal floor, moving with a speed $$v$$. It makes an elastic collision with a smooth vertical wall. After impact,
  • it will move with a speed $$v$$ initially.
  • its motion will be rolling without slipping.
  • its motion will be rolling with slipping initially and its rotational motion will stop momentarily at some instant.
  • its motion will be rolling without slipping only after some time.
Two blocks A and B of masses m and 2m respectively placed on a smooth floor are connected by a spring. A third body C of mass m moves with velocity $$v_0$$ along the line joining A and B and collides elastically with A. At a certain instant of time after collision it is found that the instantaneous velocities of A and B are same then :
168651_4342409b24a94530b5c92491729c2ab2.PNG
  • the common velocity of A and B at time t$$_0$$ is v/3.
  • the spring constant is k $$= \displaystyle \frac{3mv_0^2}{2x_0^2}$$.
  • the spring constant is k $$= \displaystyle \frac{2mv_0^2}{3x_0^2}$$.
  • none of these
The speed of the striking mass after collision is

161158.PNG
  • $$u/2$$ backwards
  • $$0$$
  • $$u/3$$ in same direction
  • $$u/7$$ backwards
0:0:1


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Practice Class 11 Medical Physics Quiz Questions and Answers