CBSE Questions for Class 11 Engineering Physics Work,Energy And Power Quiz 1 - MCQExams.com

This question has statement 1 and statementOf the four choices given after the statements, choose the one that best describes the two statements.
If two springs $$\mathrm{S}_{1}$$ and $$\mathrm{S}_{2}$$ of the force constants $$\mathrm{k}_{1}$$ and $$\mathrm{k}_{2}$$, respectively, are stretched by the same force, it is found that more work is done on spring $$\mathrm{S}_{1}$$ than on spring $$\mathrm{S}_{2}$$.
Statement-l : When stretched by the same amount, work done on $$\mathrm{S}_{1}$$, will be more than that of $$\mathrm{S}_{2}$$
Statement-2: $$\mathrm{k}_{1}<\mathrm{k}_{2}$$.
  • Statement-1 is false, statement-2 is true
  • Statement-1 is true, statement-2 is false
  • Statement-1 is true, statement-2 is true, statement 2 is the correct explanation of statement- 1
  • Statement-1 is true, statement-2 is true, statement-2 is not the correct explanation of Statement-1
When a rubber-band is stretched by a distance $$x$$, it exerts a restoring force of magnitude $$F = ax + bx^2$$ where $$a$$ and $$b$$ are constants. The work done in stretching the unstretched rubber band by $$L$$ is
  • $$\displaystyle \dfrac{aL^2}{2} + \dfrac{bL^3}{3}$$
  • $$\displaystyle \dfrac{1}{2} \left ( \dfrac{aL^2}{2} + \dfrac{bL^3}{3}\right )$$
  • $$aL^2 + bL^3$$
  • $$\displaystyle \dfrac{1}{2} (aL^2 + bL^3)$$
If collision between the block and the incline is completely elastic, then the vertical (upward) component of the velocity of the block at point B, immediately after it strikes the second incline is
43029.PNG
  • $$\sqrt{30}\mathrm{m}/\mathrm{s}$$
  • $$\sqrt{15}\mathrm{m}/\mathrm{s}$$
  • 0
  • $$-\sqrt{15}\mathrm{m}/\mathrm{s}$$
The balls, having linear momenta $$\vec{\mathrm{p}}_{1}=\mathrm{p}\hat{i}$$ and $$\vec{\mathrm{p}}_{2}=-\mathrm{p}\hat{\mathrm{i}}$$, undergo a collision in free space. There is no extemal force acting on the balls. Let $$\vec{\mathrm{p}}_{1}$$ and $$\vec{\mathrm{p}}_{2}$$ be their final momenta. The following option(s) is (are) NOT ALLOWED for any non-zero value of $$\mathrm{p},\ \mathrm{a}_{1},\ \mathrm{a}_{2},\ \mathrm{b}_{1},\ \mathrm{b}_{2},\ \mathrm{c}_{1}$$ and $$\mathrm{c}_{2}$$.
  • $$\vec{\mathrm{p}}_{1}=\mathrm{a}_{1}\hat{i}+\mathrm{b}_{1}\hat{\mathrm{j}}+\mathrm{c}_{1}\hat{\mathrm{k}}$$;

    $$\vec{\mathrm{p}}_{2}=\mathrm{a}_{2}\mathrm{i}+\mathrm{b}_{2}\hat{\mathrm{j}}$$
  • $$\vec{\mathrm{p}}_{1}=\mathrm{c}_{1}\hat{\mathrm{k}}$$;

    $$\vec{\mathrm{p}}_{2}=\mathrm{c}_{2}\hat{\mathrm{k}}$$
  • $$\vec{\mathrm{p}}_{1}=\mathrm{a}_{1}\mathrm{i}+\mathrm{b}_{1}\hat{\mathrm{j}}+\mathrm{c}_{1}\hat{\mathrm{k}}$$;

    $$\vec{\mathrm{p}}_{2}=\mathrm{a}_{2}\hat{\mathrm{i}}+\mathrm{b}_{2}\hat{\mathrm{j}}-\mathrm{c}_{1}\hat{\mathrm{k}}$$
  • $$\vec{\mathrm{p}}_{1}=\mathrm{a}_{1}\hat{\mathrm{i}}+\mathrm{b}_{1}\hat{\mathrm{j}}$$;

    $$\vec{\mathrm{p}}_{2}=\mathrm{a}_{2}\mathrm{i}+\mathrm{b}_{1}\hat{\mathrm{j}}$$
What is the minimum velocity with which a body of mass $$m$$ must enter a vertical loop of radius $$R$$ so that it can complete the loop?
  • $$\sqrt{gR}$$
  • $$\sqrt{2gR}$$
  • $$\sqrt{3gR}$$
  • $$\sqrt{5gR}$$
Two similar spring P and Q have spring constants $$K_P$$ and $$K_Q$$, such that $$K_P > K_Q$$. They are stretched, first by the same amount (case a), then by the same force (case b). The work done by the spring $$W_P$$ and $$W_Q$$ are related as, in case (a) and case (b), respectively:
  • $$W_P > W_Q; W_Q > W_P$$
  • $$W_P < W_Q; W_Q < W_P$$
  • $$W_P = W_Q; W_P > W_Q$$
  • $$W_P = W_Q; W_P = W_Q$$
The force on a particle as the function of displacement x(in x-direction) is given by $$F=10+0.5x$$
The work done corresponding to displacement of particle from $$x=0$$ to $$x=2$$ unit is?
  • $$25$$ J
  • $$29$$ J
  • $$21$$ J
  • $$18$$ J
A ball is suspended by a thread of length L at the point O on a wall which is inclined to the vertical by $$\alpha$$. The thread with the ball is displaced by a small angle $$\beta$$ away from the vertical and also away from the wall. If the ball is released, the period of oscillation of the pendulum when $$\beta > \alpha$$ will be 
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[\pi+2sin^{-1}\frac{\alpha}{\beta}\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[\pi-2sin^{-1}\frac{\alpha}{\beta}\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[2sin^{-1}\frac{\alpha}{\beta}-\pi\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[2sin^{-1}\frac{\alpha}{\beta}+\pi\right]$$
How much work must be done by a force on $$50\ $$$$kg$$ body in order to accelerate it from rest to $$20\ m/s$$  in $$10\ $$$$s$$ ?
  • $$10^3\ $$$$J$$
  • $$10^4\ $$$$J$$
  • $$2\times 10^3\ $$$$J$$
  • $$4\times 10^4\ $$$$J$$
The amount of work done in stretching a spring from a stretched length of 10 cm to a stretched length of 20 cm is-
  • Equal to the work done in stretching it from 20 cm to 30 cm
  • Less than the work done in stretching it from 20 cm to 30 cm.
  • More than the work done in stretching it from 20 cm to 30 cm.
  • Equal to the work done in stretching it from 0 to 10 cm.
A ball tied to a string is swung in a vertical circle. Which of the following remains constant?
  • Tension in the string.
  • Speed of the ball.
  • Centripetal force.
  • Earth's pull on the ball.
The K.E. of a body can be increased maximum by doubling its:
  • mass
  • weight
  • speed
  • density
A lighter body moving with a velocity $$v$$ collides with a heavier body at rest. Then :
  • the lighter body rebounces with twice the velocity of bigger body
  • the lighter body retraces its path with the same velocity in magnitude
  • the heavier body does not move practically
  • both (2) and (3)
A certain force acting on a body of mass 2kg increase its velocity from 6m/s to 15 m/s in 2s. The work done by the force during this interval is ?
  • 27J
  • 3J
  • 94.5J
  • 189J
Name the type of energy (kinetic energy $$K$$ or potential energy $$U$$) possessed in a compressed spring:
  • $$U$$
  • $$K$$
  • Both $$U$$ and $$K$$
  • None
Energy equals of a mass of one microgram in kilo joules is
  • $$9 \times 10^{7} kJ$$
  • $$10 \times 10^3 kJ$$
  • $$8 \times 10^2 kJ$$
  • $$7 \times 10^4 kJ$$
A particle moves under the effect of a force $$F=Cx$$ form $$x=0$$ to $$x=x_{1}$$. The work done in the process is-
  • $$Cx_{1}^{2}$$
  • $$\displaystyle \frac{1}{2}Cx_{1}^{2}$$
  • $$Cx_{3}^{2}$$
  • zero
A stone tied to a string is rotated in a vertical circle. The minimum speed with which the stone has to be rotated in order to complete the circle :
  • decreases with increasing the mass of the stone
  • is independent of the mass of the stone
  • decreases with increasing the length of the string
  • is independent of the length of the string
Complete the following sentence:
The kinetic energy of a body is the energy by virtue of its______ .
  • force
  • motion
  • roughness
  • all the above
A simple pendulum, composed of a bob of mass $$m$$ connected to the end of a massless rod, executes simple harmonic motion as it swings through small angles of oscillation.The maximum angular displacement with the vertical is denoted by $${ \theta  }_{ max }$$. Frictional effects and variation of acceleration due to gravity are negligible.  
Find out the correct statement?
480285.jpg
  • At $$\theta=0$$, the tangential acceleration is $$0$$
  • At $$\theta={\theta}_{max}$$, the tangential acceleration is $$0$$
  • At $$\theta=0$$, the speed is $$0$$
  • At $$\theta=0$$, the restoring force is maximized
  • At $$\theta={\theta}_{max}$$, the speed is maximized
Which of the following will lead to a change in kinetic energy of a body?
  • change in its mass
  • change in its velocity
  • all of the above
  • none of the above
What is potential energy?
  • Energy of an object due to its position or arrangement in a system
  • Energy of an object due to its nature or arrangement in a system
  • Energy of an object due to its shape or arrangement in a system
  • None
A physics student is performing a experiment in which she twirls  rubber stopper at the end of a string around in a circle at nearly constant speed and tries to determine its acceleration. Which of the following single changes would enables her to most nearly double the acceleration of the rubber stopper?
  • Double the speed of the rubber stopper.
  • Use a string that is twice as long as the original string.
  • Reduce the speed of the rubber stopper to half its original value.
  • Use a string that is half as long as the original string
  • Use a rubber stopper with twice as much mass as the original rubber stopper.
A ride in an amusement park called scream machine swings the riders around a complete vertical circle during the course of the ride.
Identify where on ride rider feels the maximum speed?

480094_fcf3fe22ce1246bfb552fb674d215e0f.png
  • Point A
  • Point B
  • Point C
  • Point D
  • Point E
A ball of mass $$m$$ is attached with the string of length $$R$$, rotating in a circular motion, with instantaneous velocity $$v$$ and centripetal acceleration $$a$$.
Calculate the centripetal acceleration of the ball if its mass is doubled?
  • $${a}/{4}$$
  • $${a}/{2}$$
  • $$a$$
  • $$2a$$
  • $$4a$$
A simple pendulum, composed of a bob of mass $$m$$ connected to the end of a massless rod, executes simple harmonic motion as it swings through small angles of oscillation.The maximum angular displacement with the vertical is denoted by $${ \theta  }_{ max }$$. Frictional effects and variation of acceleration due to gravity are negligible.  
Which one of the following would enable you to calculate the length of the pendulum?
480287.jpg
  • The mass of the bob
  • The period of the oscillations
  • The tangential acceleration at $$\theta = 0$$
  • The maximum speed of the bob
  • The acceleration at $$\theta = {\theta}_{max}$$
In the phenomenon of work done by variable forces, the forces:
  • remain constant
  • don't remain constant
  • increase
  • decrease
A ball with mass m and speed $$V_0$$ hit a wall and rebounds back with same speed.
Calculate the change in the object's kinetic energy.
  • $$-mv_0 ^2$$
  • $$- \frac{1}{2}mv_0 ^2$$
  • Zero
  • $$ \frac{1}{2}mv_0 ^2$$
  • $$mv_0 ^2$$
What is kinetic energy?
  • Energy possessed by a body by the virtue of its motion
  • Energy possessed by a body by the virtue of its shape
  • Energy possessed by a body by the virtue of its size
  • None
A particle moves from $$X = 0\ $$ to $$X = 2\ m$$ on X-axis under the effect of $$ { F } (x) = ({ 4x }^{ 3 } - { 3x }^{ 2 } + 2x + 5)\widehat { i } $$ Newton. The work done on the particle is 
  • $$ 22\ Joule$$
  • $$ 36\ Joule$$
  • $$ 46\ Joule$$
  • None of these
A force of $$16N$$ is distributed uniformly on one surface of a cube of edge $$8cm$$. The pressure on this surface is 
  • $$3500Pa$$
  • $$2500Pa$$
  • $$4500Pa$$
  • $$5500Pa$$
A brick of mass $$m$$ , tied to a rope , is being whirled in a vertical circle, with a uniform speed. The tension in the rope is:
  • The same throughout
  • Largest when the brick is at the highest point of the circular path and smallest when it is at the lowest point
  • Largest when the rope is horizontal and smaller when it is vertical.
  • Largest when the brick is at the lowest point of the circular path and smallest when it is at the highest point
A $$\vec{F}=(5\hat{i}+3\hat{j}+2\hat{k})\ N$$ is applied over a particle with displaces it from its origin to the point $$\vec{r}=(2\hat{i}-\hat{j})m$$. The work done on the particle is joule is
  • $$-7\ J$$
  • $$+7\ J$$
  • $$+10\ J$$
  • $$13\ J$$
A force F = $$-\frac{K}{X^2} (X \neq 0)$$ acts on a particle in x-direction. The work done by this force in displacing the particle from x = +a to x = +2a is. (Where k is a positive constant)
  • $$\frac{-k}{2a}$$
  • $$\frac{+k}{2a}$$
  • $$\frac{k}{a}$$
  • $$-\frac{k}{a}$$
Given $$k_1 = 1500 \ N/m,$$ $$k_2 =500 \ N/m,$$ $$m_1 = 2 \ kg$$ and $$m_2 = 1  \ kg$$. Find potential energy stored in equilibrium: (Take $$g = 10 \ m/s^2$$)

4288_2ebb643528c04b1f9e3d7e770df4162d.png
  • 2.3 J
  • 0.4 J
  • 3.4 J
  • 0.6 J
A ball of mass $$'m'$$ moves towards a wall with a velocity $$'u'$$, the direction of motion making an angle $$\theta$$ with the surface of the wall and rebounds with the same period. The change in momentum of the ball during the collision is:
  • $$2mu\  sin$$$$\theta$$ towards the wall
  • $$2mu \ sin$$$$\theta$$ away from the wall
  • $$2mu\  cos$$$$\theta$$ towards the wall
  • $$2mu\  cos$$$$\theta$$ away from the wall
 A car of mass 400 kg travelling at 72 kmph crashes a truck of mass 4000 kg and travelling at 9 kmph in the same direction. The car bounces back with a speed of 18 kmph. The speed of the truck after the impact is
  • 9 kmph
  • 18 kmph
  • 27 kmph
  • 36 kmph
 A perfectly elastic ball $$p_{1}$$of mass 'm' moving with velocity v collides elastically with three exactly similar balls $$p_{2}$$ , $$p_{3}$$ , $$p_{4}$$  lying on a smooth table. Velocities of the four balls after collision are

Image_p3.png
  • 0,0,0,0
  • v,v,v,v
  • v,v,v,0
  • 0,0,0,v
A particle moves under the effect of a force $$F = C x$$ from $$x = 0$$ to $$ x = x_{1}$$. The work done in the process is (treat $$C$$ as a constant):
  • $$ \dfrac {C^{2}}{x^{2}_{1}}$$
  • $$Cx^{2}_{1}$$
  • $$ \dfrac {Cx^{2}_{1}}{2}$$
  • $$ \dfrac {C}{x^{2}_{1}}$$
A ball of mass M moving with a velocity V collides head on elastically with another of same mass but moving with a velocity v in the opposite direction. After collision,
  • the velocities are exchanged between the two balls
  • both the balls come to rest
  • both of them move at right angles to the original line of motion
  • one ball comes to rest and another ball travels back with velocity 2V
 A heavy steel ball of mass greater than 1 kg moving with a speed of 2m/ s collides head on with a stationary ping pong ball of mass less than 0.1 g. The collision is elastic. After the collision the ping pong ball moves approximately with a speed
  • $$ 2 m / s $$
  • $$4 m/ s$$
  • $$2\times10^{4}m / s$$
  • $$2\times10^{3}m / s$$
 A heavier body moving with certain velocity collides head on elastically with a lighter body at rest. Then
  • smaller body continues to be in the same state of rest
  • smaller body starts to move in the same direction with same velocity as that of bigger body
  • the smaller body starts to move with twice the velocity of the bigger body in the same direction
  • the bigger body comes to rest
A body of mass 2 kg is at rest. A force of $$4\hat{i} + 3\hat{j} - 5\hat{k}$$ N acts on it and displaces through $$2\hat{i} + \hat{j} + 2\hat{k}$$ m. The velocity acquired by the body is:
  • $$0\ ms^{-1}$$
  • $$1\ ms^{-1}$$
  • $$2\ ms^{-1}$$
  • $$ 10\ ms^{-1}$$
A rain drop of mass (1/10) gram falls vertically at constant speed under the influence of the forces of gravity and viscous drag. In falling through 100 m, the work done by gravity is
  • 0.98 J
  • 0.098 J
  • 9.8 J
  • 98 J
 A sphere of mass m moving with constant velocity u, collides with another stationary sphere of same mass. If e is the coefficient of restitution, the ratio of the final velocities of the first and second sphere is
  • $$\dfrac{1+e}{1-e}$$
  • $$\dfrac{1-e}{1+e}$$
  • $$\dfrac{e}{1-e}$$
  • $$\dfrac{1+e}{e}$$
 A ball moving with a speed of 2.2 m/sec strikes an identical stationary ball. After collision the first ball moves at 1.1 m/sec at $$60^{0}$$  with the original line of motion. The magnitude and direction of the ball after collision is 
  • $$5 m/sec,90^{0}$$
  • $$2 m/sec,60^{0}$$
  • $$\sqrt{39(1.1)}m/sec,30^{0}$$
  • $$10m/sec,60^{0}$$
A 50 gm ball collides with another ball of mass 150gm, moving in its direction of motion, After collision the two balls move at a an angle $$30^{0}$$ with their initial direction. Ratio of their velocities after collision is
  • 3 : 1
  • 1 : 3
  • 2 : 3
  • 1 : 1
 A body of mass 5 kg moving with a speed of $$ 3 ms^{-1}$$ collides head on with a body of mass 3 kg moving in the opposite direction at a speed of $$2 ms^{-1}$$. The first body stops after the collision. Find the final velocity of the second body.
  • $$3 ms^{-1}$$
  • $$5 ms^{-1}$$
  • $$-9 ms^{-1}$$
  • $$30 ms^{-1}$$
A body is moving in a vertical circle such that the velocities of body at different points are critical. The ratio of velocities of body at angular displacements $$60^{0}$$ and $$120^{0}$$ from the lowest point is:
  • $$\sqrt{5}:\sqrt{2}$$
  • $$\sqrt{3}:\sqrt{2}$$
  • $$\sqrt{3}:1$$
  • $$\sqrt{2}:1$$
A simple pendulum is oscillating with an angular amplitude $$60^{0}$$ . If mass of bob is $$50\ g$$, the tension in the string at mean position is:
Consider: $$g=10ms^{-2}$$, length of the string, $$L = 1\ m$$.
  • $$0.5\ N$$
  • $$1\ N$$
  • $$1.5\ N$$
  • $$2\ N$$
0:0:1


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