CBSE Questions for Class 11 Medical Physics Work, Energy And Power Quiz 3 - MCQExams.com

 In a hydro power plant:
  • Potential energy possessed by stored water is converted into electricity
  • Kinetic energy possessed by stored water is converted into potential energy
  • Water is heated to produce electricity
  • Water is converted into steam to produce electricity
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
Determine the energy released in the process
$$_1H^2+_1H^2\rightarrow _2He^4+Q$$
Given $$M(_1H^2)=2.01471 amu M(_2He^4)=4.00388 amu$$
  • 3.79 MeV
  • 13.79 MeV
  • 0.79 MeV
  • 23.79 MeV
An open knife of mass $$m$$ is dropped from a height $$h$$ on a wooden floor. If the blade penetrates up to the depth $$d$$ into the wood, the average resistance offered by the wood to the knife edge is:
  • $$mg(1+\dfrac {h}{d})$$
  • $$mg(1+\dfrac {h}{d})^2$$
  • $$mg(1-\dfrac {h}{d})$$
  • $$mg(1+\dfrac {d}{h})$$
A particle moves along the x-axis from $$x=0$$ to $$x=5$$ m under the influence of a force given by $$F=7-2x+3x^2$$. The work done in the process is
  • 360 J
  • 85 J
  • 185 J
  • 135 J
A ball is projected upwards. As it rises, there is increase in its:
  • Momentum
  • Retardation
  • Kinetic energy
  • Potential energy
An open knife of mass $$m$$ is dropped from a height $$h$$ on a wooden floor. If the blade penetrates up to the depth $$d$$ into the wood, the average resistance offered by the wood to the knife edge is
  • $$mg(1+\displaystyle \frac{h}{d})$$
  • $$mg(1+\displaystyle \frac{h}{d})^{2}$$
  • $$mg(1-\displaystyle \frac{h}{d})$$
  • $$mg(1+\displaystyle \frac{d}{h})$$
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 $$\dfrac {v_0}{\sqrt 2}$$. Then the speed of the particle of mass $$2m_0$$ after this collision is
  • $$\dfrac {v_0}{2}$$
  • $$\dfrac {v_0}{2\sqrt 2}$$
  • $$\sqrt 2v_0$$
  • $$\dfrac {v_0}{\sqrt 2}$$
A sphere of mass m moving with a constant velocity collides with another stationary sphere of same mass. The ratio of velocities of two spheres after collision will be, if the co-efficient of restitution is e:
  • $$\displaystyle \frac{1 - e}{1 + e}$$
  • $$\displaystyle \frac{e - 1}{e + 1}$$
  • $$\displaystyle \frac{1 + e}{1 - e}$$
  • $$\displaystyle \frac{e + 1}{e - 1}$$
A locomotive of mass $$m$$ has a velocity $$v = a \sqrt{x}$$. Find the work done by all the forces acting on locomotive in first $$t$$ sec.
  • $$\displaystyle \frac{ma^2 t^2}{4}$$
  • $$\displaystyle \frac{ma^4 t^2}{4}$$
  • $$\displaystyle \frac{ma^4 t^2}{8}$$
  • $$\displaystyle \frac{ma^4 t^2}{2}$$
what is the work done by a force $$4N$$ in moving the body from d $$=$$ 1m to 4m?
  • 6 J
  • 16 J
  • 12 J
  • 8 J
A heavy ball moving with speed $$v$$ collides with a tiny ball. The collision is elastic, then immediately after the impact, the second ball will move with a speed approximately equal to-
  • $$v$$
  • $$2v$$
  • $$\dfrac {v}{2}$$
  • $$\dfrac {v}{3}$$
A body of mass $$m$$ is accelerated to velocity $$v$$ in time $$t'$$. The work done by the force as a function of time $$t$$ will be
  • $$\displaystyle \frac{m}{2} \frac{v^2 t^2}{t'^2}$$
  • $$\displaystyle \frac{1}{2} \left ( \frac{mv}{t'} \right )^2 t^2$$
  • $$\displaystyle \frac{m}{2} \frac{v}{t'} t^2$$
  • $$\displaystyle \frac{mvt^2}{2t'}$$
When an arrow is released from a bow, potential energy changes into kinetic energy.
  • True
  • False
  • Ambiguous
  • Data insufficient
A body moving towards a finite body at rest collides with it. It is possible that:
  • both the bodies come to rest
  • both the bodies moves after collision
  • the moving body comes to rest and the stationary body starts moving
  • the stationary body remains stationary, the moving body changes its velocity
A ball of mass $$m$$ moving with velocity $$v$$ collides elastically with wall and rebounds. The change in momentum of the ball will be :
  • $$4 mv$$
  • $$2 mv$$
  • $$mv$$
  • $$zero$$
A mass $$m_1$$ moves with a great velocity. It strikes another mass $$m_2$$ at rest in a head on collision and comes back along its path with a low speed after collision. Then :
  • $$m_1 > m_2$$
  • $$m_1 = m_2$$
  • $$m_1 < m_2$$
  • there is relation between $$m_1$$ and $$m_2$$
A ball with velocity $$9\ m/s$$ collides with another similar stationary ball. After the collision the two balls move in directions making an angle of  $$30^o$$ with the initial direction. The ratio of the speeds of balls after the collision will be :
138439_8f0c02b951344cb5b82ba5bcc930f0f5.png
  • $$\displaystyle \dfrac{v_1}{v_2} = 1$$
  • $$\displaystyle \dfrac{v_1}{v_2} > 1$$
  • $$\displaystyle \dfrac{v_1}{v_2} < 1$$
  • $$\displaystyle \dfrac{v_1}{v_2} = 0$$
A particle at rest on a frictionless table is acted on by a horizontal force, which is constant in magnitude and direction. A graph is plotted for the work done on the particle $$W$$, against the speed of the particle $$v$$. If there are no frictional force acting on the particle, the graph will look like:
A bullet weighing 10 g and moving at 300 ms$$^{-1}$$ strikes a 5 kg block of ice and drops dead. The ice block is sitting on frictionless level surface. The speed of the block, after the collision is :
  • 60 ms$$^{-1}$$
  • 3 ms$$^{-1}$$
  • 6 ms$$^{-1}$$
  • 0.6 ms$$^{-1}$$
A steel ball moving with a velocity $$\overline{v}$$ collides with an identical ball originally at  rest. The velocity of the first ball after the collision is :
  • $$\left(-\dfrac{1}{2}\right)\overline{v}$$
  • $$-\overline{v}$$
  • $$\overline{v}$$
  • zero
A massive ball moving with a speed $$v$$ collide with a tiny ball having a very small mass , immediately after the impact the second ball will move at speed approximately equal to :
  • $$\infty$$
  • $$\dfrac{v}{2}$$
  • $$v$$
  • $$2v$$
A sphere of mass $$m$$ moving with a constant velocity $$v$$ hits another stationary sphere of the same mass. If $$e$$ is the coefficient of restitution, then the ratio of the velocities of the first sphere to the second spheres after the collision will be :
  • $$\left(\dfrac{1+e}{1-e}\right)$$
  • $$\left(\dfrac{e-1}{e+1}\right)$$
  • $$\left(\dfrac{1-e}{e+1}\right)$$
  • $$\left(\dfrac{1+e}{e-1}\right)$$
Under the action of a force, a 2kg mass moves such that its position x as a function of time t is given by $$x=t^3/3$$ where x is in meters and t in second. The work done by the force in first two seconds is:
  • 1600 joule
  • 160 joule
  • 16 joule
  • 1.6 joule
What will be the potential energy of a body of mass 5 kg kept at a height of 10 m ?
  • 50 J
  • 0.5 J
  • 500 J
  • 25 J
At what value of $$\eta$$ will the velocity of the disc after the collision reverse its direction?
  • $$\eta<4$$
  • $$\eta>4$$
  • $$\eta=4$$
  • $$\eta=0$$
At what value of $$\eta$$ will the velocity of the disc after the collision be equal to zero?
  • $$\eta=4$$
  • $$\eta=5$$
  • $$\eta=6$$
  • $$\eta=7$$
In the elastic collision of heavy vehicle moving with a velocity 10 ms$$^{-1}$$ and a small stone at rest, the stone will fly away with a velocity equal to : 
  • 40 ms$$^{-1}$$
  • 20 ms$$^{-1}$$
  • 10 ms$$^{-1}$$
  • 5 ms$$^{-1}$$
A sphere of mass m, moving with a speed v, strikes a wall elastically at an angle of incidence $$\theta$$. If the speed of the sphere before and after collision is the same and the angle of incidence and velocity normally towards the wall the angle of rebound is equal to the angle of incidence and velocity normally towards the wall is taken as negative then, the change in the momentum parallel to wall is :
  • mv cos $$\theta$$
  • 2mv cos $$\theta$$
  • -2mv cos $$\theta$$
  • zero
The blocks of masses $$m_1$$ and $$m_2$$ are connected by an ideal spring of force constant k. The blocks are placed on a smooth horizontal surface. A horizontal force F acts on the block $$m_1$$. Initially, spring is relaxed, both the blocks are at rest.
What is the maximum elongation of spring?
  • $$\displaystyle \frac{2m_1 F}{(m_1 + m_2)k}$$
  • $$\displaystyle \frac{m_1^2 F}{2(m_1 + m_2)^2 k}$$
  • $$\displaystyle \frac{m_2 F}{k (m_1 + m_2)}$$
  • $$\displaystyle \frac{m_2^2 F}{2(m_1 + m_2)^2k}$$
Two objects that are moving along an xy-plane on a frictionless floor collide. Assume that they form a closed, isolated system. The following table gives some of the momentum components (in kilogram meters per second) before and after the collision. What are the mission values (a, b):
Before collisionAfter collision
ObjectP$$_x$$P$$_y$$P$$_x$$P$$_y$$
A-453a
Bb-242
  • 10, 11
  • 1, 11
  • 5, 7
  • 6, 4
The hydroelectric plants do not produce electricity, if the water level in the dam is less than 34 m.
  • True
  • False
  • Ambiguous
  • Data insufficient
Find the velocity of the disc after the collision.
  • $$\displaystyle v^\prime=\frac{4+\eta}{4+\eta}v$$
  • $$\displaystyle v^\prime=\frac{4-\eta}{4-\eta}v$$
  • $$\displaystyle v^\prime=\frac{4-\eta}{4+\eta}v$$
  • $$\displaystyle v^\prime=\frac{4+\eta}{4-\eta}v$$
A bullet moving with a velocity of 800 ms$$^{-1}$$ strikes two wooden plates of widths $$x_1$$ and $$x_2$$ and in passing through each of them loses 200 ms$$^{-1}$$ of its velocity. Assuming the resistance of the plates to be uniform, the ratio $$x_1 : x_2$$ is   
  • $$\dfrac{7}{5}$$
  • $$\dfrac{5}{3}$$
  • $$\dfrac{9}{7}$$
  • $$\displaystyle \dfrac{15}{13}$$
Two masses $$m_a$$ and $$m_b$$ moving with velocities $$v_a$$ and $$v_b$$ in opposite direction collide elastically and after the collision $$m_a$$ and $$m_b$$ move with velocities $$v_b$$ and $$v_a$$ respectively. Then the ratio $$m_a/m_b$$ is :
  • $$\displaystyle \frac{V_a-V_b}{V_a+V_b}$$
  • $$\displaystyle \frac{m_a+m_b}{m_a}$$
  • 1
  • $$\displaystyle \frac{1}{2}$$
A pump is used to lift $$500\ kg$$ of water from a depth of $$80\ m$$ in $$10\ s$$.
(Take $$g=10\ ms^{-2}$$). Calculate the work done by the pump.
  • $$16 \times 10^5J$$
  • $$4\times 10^5J$$
  • $$4\times 10^8J$$
  • $$2\times 10^5J$$
A particle moves under the effect of a force $$F=cx$$ from $$x=0$$ to $$x=x_1$$, the work done in the process is
  • $$cx_1^2$$
  • $$\displaystyle \frac{1}{2} cx_1^2$$
  • $$2cx_1^2$$
  • zero
Name the type of energy (kinetic energy $$K$$ or potential energy $$U$$) possessed in the following case.
A piece of stone placed on the roof.
  • $$U$$
  • $$K$$
  • $$U$$ and $$K$$
  • No energy
A body starts from rest and acquires a velocity $$V$$ in time $$T$$ at constant rate. The work done on the body in time $$t$$ will be proportional to
  • $$\displaystyle \frac{V}{T}t$$
  • $$\displaystyle \frac{V^2}{T}t^2$$
  • $$\displaystyle \frac{V^2}{T^2}t$$
  • $$\displaystyle \frac{V^2}{T^2}t^2$$
Two solid rubber balls $$A$$ and $$B$$ having masses $$200\ \&\ 400\ \text{gm}$$ respectively are moving in opposite direction with velocity of $$A$$ equal to $$0.3\ \text{m/sec}.$$ After collision the two balls come to rest when the velocity of $$B$$ is :
  • $$0.15\ \text{m/sec}$$
  • $$1.5\ \text{m/sec}$$
  • $$-0.15\ \text{m/sec}$$
  • $$\text{None of these}$$
Work is always done on a body when :
  • a force acts on it
  • it moves through a certain distance
  • it experiences an increase in energy through a mechanical influence
  • none of these
Name the type of energy (kinetic energy $$K$$ or potential energy $$U$$) possessed in the following case.
The bob of a simple pendulum at its extreme position.
  • $$K$$
  • $$U$$
  • $$K$$ and $$U$$
  • No energy
A ball is dropped from a height of 10 m. If the energy of the ball reduces by 40% after striking the ground, how high can the ball bounce back? $$(g=10 \: m \: s^{-2})$$
  • 6 m
  • 10 m
  • 3 m
  • 12 m
A man raises a box of mass $$50 \ kg$$ to a height of $$2 \ m$$ in $$2 \ minutes$$, while another man raises the same box to the same height in $$5 \ minutes$$. What is the ratio of work done by them ?
  • $$1 : 1$$
  • $$2 : 1$$
  • $$1 : 2$$
  • $$4 : 1$$
A block is acted upon by a force, which is inversely proportional to the displacement $$x$$. The work done will be proportional to
  • $$x$$
  • $$x^{1/2}$$
  • $$x^2$$
  • none of these
Identify the correct statement about work energy theorem
  • work done by all the conservative forces is equal to the decrease in potential energy.
  • work done by all the forces except the conservative forces is equal to the change in mechanical energy.
  • work done by all the forces is equal to the change in kinetic energy.
  • work done by all the forces is equal to the change in potential energy.
A block of mass $$m=2$$ kg is pulled by a force $$F=40$$ N upwards through a height $$h=2 m$$. Find the work done on the block by the applied force F and its weight mg. $$\displaystyle \left ( g= 10 m/s^{2} \right )$$
238713.bmp
  • $$\displaystyle W_F = 80 J;W_{mg}= -40 J$$
  • $$\displaystyle W_F = 80 J;W_{mg}= 40 J$$
  • $$\displaystyle W_F = -80 J;W_{mg}= -40 J$$
  • $$\displaystyle W_F = -80 J;W_{mg}= 40 J$$
A force $$F$$ acting on a particle varies with the position $$x$$ as shown in figure. Find the work done by this force in displacing the particle from $$\displaystyle x= 0\ m\:to\:x= 2\  m.$$
238954_06a60bc283874bfbb28d16d2032b88e2.png
  • $$-10J$$
  • $$10J$$
  • $$5J$$
  • $$-5J$$
A smooth sphere $$A$$ is moving on a frictionless horizontal plane with angular speed $$\omega$$ and centre of mass velocity $$v$$. It collides elastically and head on with an identical sphere $$B$$ at rest. Neglect friction everywhere. After the collision, their angular speeds are $$\omega_A$$ and $$\omega_B$$, respectively. Then
  • $$\omega_A < \omega_B$$
  • $$\omega_A = \omega_B$$
  • $$\omega_A = \omega$$
  • $$\omega_B = \omega$$
By stretching the rubber strings of a catapult we store .......... energy in it.

211981_520a63f02040490eaf6e77e84c2ff04d.jpg
  • $$potential$$
  • $$electrical$$
  • $$heat$$
  • $$kinetic$$
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