CBSE Questions for Class 11 Engineering Physics Work,Energy And Power Quiz 4 - MCQExams.com

State whether the given statement is True or False :
The energy of an object that is due to the object's motion is called kinetic energy.
  • True
  • False
A boy is whirling a stone tied at one end such that the stone is in uniform circular motion.Which of the following statement is correct?
245814_7d3f89bb93574ce29b4797732a70bd81.png
  • The velocity of stone at A is equal to the velocity of stone B
  • The speed of stone at A is equal to the speed of stone at B.
  • The centripetal force is radially outward in the string.
  • All of the above statements are correct.
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process, the potential energy of the car
  • does not change
  • becomes twice of initial
  • becomes 4 times of initial
  • becomes 16 times of initial
A mass is performing vertical circular motion (see figure). If the average velocity of the particle is increased, then at which point is the maximum breaking possibility of the string:
280422.bmp
  • A
  • B
  • C
  • D
A stone of mass $$1\;kg$$ is tied to the end of a string of $$1\;m$$ long. It is whirled in a vertical circle. If the velocity of the stone at the top be $$4\;m/s$$. What is the tension in the string?
  • $$\;6\;N$$
  • $$\;16\;N$$
  • $$\;5\;N$$
  • $$\;10\;N$$
Two weights of 5 kg and 10 kg are placed on a horizontal table of height 1.5 m. Which will have more potential energy?
  • 5 kg
  • 10 kg
  • Both will have equal energy
  • None of the above
Which one of the following possesses potential energy?
  • Moving vehicle on the road
  • A running athlete
  • Stone on the road
  • A stretched rubber band
An overhead tank having some water possesses .......... energy.
  • Kinetic
  • Potential
  • Thermal
  • Electrical
When an arrow is released from a bow, potential energy changes into kinetic energy.
  • True
  • False
  • Ambiguous
  • Data insufficient
Energy possessed by a body by virtue of its motion is :
  • Potential energy
  • Kinetic energy
  • Chemical energy
  • Electrical energy
A student sitting at the top of a tree has ............ than the student who is sitting on the ground.
  • less potential energy
  • more potential energy
  • more kinetic energy
  • more gravitational energy
The form of energy present in a wound spring is:
  • chemical
  • heat energy
  • magnetic
  • mechanical
The energy directly related to the speed of a moving body and its mass is:
  • Kinetic
  • Potential
  • Solar
  • Electric
A boy holds a pendulum in his hand while standing at the edge of a circular platform of radius $$r$$ rotating at an angular speed $$\omega$$. The pendulum will hang at an angle $$\theta$$ with the verticle such that
  • $$\;tan\,\theta=0$$
  • $$\;tan\,\theta=\displaystyle\frac{\omega^2r^2}{g}$$
  • $$\;tan\,\theta=\displaystyle\frac{r\omega^2}{g}$$
  • $$\;tan\,\theta=\displaystyle\frac{g}{\omega^2r}$$
A mass tied to a string moves in a vertical circle with a uniform speed of $$5\;m/s$$ as shown. At the point $$P$$ the string breaks. The mass will reach a height above $$P$$ of nearly: $$(g=10\ m/s^{2})$$
281289_9e5aee9304574026bff2f5a8515de9e6.png
  • $$\;1\;m$$
  • $$\;0.5\;m$$
  • $$\;1.75\;m$$
  • $$\;1.25\;m$$
A particle of mass $$'m'$$ describes a circle of radius $$(r)$$. The centripetal acceleration of the particle is $$\displaystyle\frac{4}{r^2}$$. The momentum of the particle:
  • $$\;\displaystyle\frac{2m}{r}$$
  • $$\;\displaystyle\frac{2m}{\sqrt{r}}$$
  • $$\;\displaystyle\frac{4m}{r}$$
  • $$\;\displaystyle\frac{4m}{\sqrt{r}}$$
In a vertical circle of radius $$(r)$$, at what point in its path a particle may have tension equal to zero:
  • highest point
  • lowest point
  • at any point
  • at a point horizontal from the centre of radius
A stone attached to one end of a string is whirled in a vertical circle. The tension in the string is maximum when
  • the string is horizontal
  • the string is vertical with the stone at highest position
  • the string is vertical with the stone at the lowest position
  • the string makes an angle of $$45^{\circ}$$ with the vertical
A position dependent force $$F=7-2x+3x^{2}$$N acts on a small object of mass 2kg to displace it from $$x=0$$ to $$x=5m$$. The work done in joules is-
  • 70
  • 270
  • 35
  • 135
A particle is moving in a vertical circle, the tension in the string when passing through two position at angle $$30^{\circ}$$ and $$60^{\circ}$$ from vertical from lowest position are $$T_1$$ and $$T_2$$ respectively, then 
  • $$T_1 = T_2$$
  • $$T_1 > T_2$$
  • $$T_1 < T_2$$
  • $$T_1\ge T_2$$
A pendulum bob has a speed $$3\;m/s$$ while passing through its lowest position, length of the pendulum is $$0.5\;m$$ then its speed when it makes an angle of $$60^{\circ}$$ with the vertical is
  • $$\;2\;m/s$$
  • $$\;1\;m/s$$
  • $$\;4\;m/s$$
  • $$\;3\;m/s$$
A particle slides from rest from the topmost point of a vertical circle of radius ($$r$$) along a smooth chord making an angle $$(\theta)$$ with the vertical the time of decent is 
  • Least for $$\theta=0^{\circ}$$
  • Maximum for $$\theta=0^{\circ}$$
  • Least for $$\theta=45^{\circ}$$
  • Independent of $$\theta$$
A particle of mass $$m_{1}$$ moving with a velocity of $$5m/s$$ collides head on with a stationary particle of mass $$m_{2}$$. After collision both the particle move with a common velocity of $$4m/s$$, then the value $$m_
{1}/m_{2}$$ is:
  • 4:1
  • 2:1
  • 1:8
  • 1:2
A time dependent force F = 10 t is applied on 10 kg block. Find out the work done by F in 2 seconds.
  • 40 J
  • 20 J
  • 120 J
  • 60 J
Force shown acts for $$2$$ seconds. Find out work done by force $$F$$ on $$10$$ kg in $$3$$ seconds.
301887_761b4a987fc1439fa0f106fe720cb995.png
  • 30 J
  • 20 J
  • 50 J
  • 60 J
A force acts on a $$3$$ gm particle in such a way that the position of the particle as a function of time is given by $$x=3t-4t^2+t^3$$, where x is in meters and t is in seconds. The work done during the first $$4$$ second is:
  • $$384 mJ$$
  • $$168 mJ$$
  • $$528 mJ$$
  • $$541 mJ$$
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
The work done by the frictional force on a surface in drawing a circle of radius r on the surface by a pencil of negligible mass with a normal pressing force N (coefficient of friction $$\mu_k$$ ) is : 
  • $$4\pi r^{2} \mu_K N$$
  • $$-2\pi r^{2} \mu_K N$$
  • $$-2\pi r \mu_K N$$
  • Zero
A bead is free to slide down a smooth wire tightly stretched between points $$A$$ and $$B$$ on a verticle circle of radius $$R$$. If the bead starts from rest at '$$A$$', the highest point on the circle, its velocity when it arrives at $$B$$ is

298025.png
  • $$2\sqrt{gR}$$
  • $$2\sqrt{gR} \cos{\theta}$$
  • $$\displaystyle \dfrac{2\sqrt{R}}{g}$$
  • None of the above
A bob hangs from a rigid support by an inextensible string of length $$\ell$$. If it is displaced through a distance $$\ell$$ (from the lowest position) keeping the string straight, & then released. The speed of the bob at the lowest position is:
293402.png
  • $$\sqrt{g\ell}$$
  • $$\sqrt{3g\ell}$$
  • $$\sqrt{2g\ell}$$
  • $$\sqrt{5g\ell}$$
A ball of mass 3 kg collides with a wall with velocity $$10\:m/sec$$ at an angle of $$30^{\circ}$$ with the wall and after collision reflects at the same angle with the same speed. The change in momentum of ball in MKS unit is-
  • 20
  • 30
  • 15
  • 45
Two equal masses are attached to the two ends of a spring of spring constant k. The masses are pulled symmetrically to stretch the spring by a length x over its natural length. The work done by the spring on each mass during the pulling is
  • $$\displaystyle \frac{1}{2}kx^{2}$$
  • $$\displaystyle -\frac{1}{2}kx^{2}$$
  • $$\displaystyle \frac{1}{4}kx^{2}$$
  • $$\displaystyle -\frac{1}{4}kx^{2}$$
The velocity of a bus, moving on a smooth road, is increased from 8 m/s to 32 m/s in 120s. During this process, the potential energy of the bus
  • Does not change
  • Becomes twice that of initial potential energy
  • Becomes four times that of initial potential energy
  • Becomes sixteen times that of initial potential energy
Two bodies P and Q of equal masses are kept at heights $$x$$ and $$4x$$ respectively. What will be the ratio of their potential energies?
  • $$1:8$$
  • $$4:1$$
  • $$1:4$$
  • $$8:1$$
An object of mass 500 g falls from a height of 2m. If $${g = 9.8 m/s^2}$$, what is its kinetic energy just before touching the ground?
  • Zero
  • 19.6 J
  • 9.8 J
  • 9800 J
What is work done in holding a body of mass $$20\ kg$$ at a height of $$2\ m$$ above the ground? $$(g = 10\ m/s^2)$$
  • $$40\ J$$
  • $$400\ J$$
  • $$10\ J$$
  • Zero
Find out work done by applied force to slowly extend the spring from x to 2x.
  • $$\dfrac{1}{2}kx^2$$
  • $$\dfrac{3}{2}kx^2$$
  • $$\dfrac{5}{2}kx^2$$
  • $$\dfrac{7}{2}kx^2$$
Initially spring is relaxed. A person starts pulling the spring by applying  a variable force $$F$$. Find out the work done by $$F$$ to stretch it slowly to a distance by $$x$$.
302034_5fcdefb9c35d4923bfff458326778809.png
  • $$\dfrac{Kx^2}{1}$$
  • $$\dfrac{Kx^2}{2}$$
  • $$\dfrac{Kx^2}{4}$$
  • $$\dfrac{Kx^2}{8}$$
How fast should a girl of 40 kg run so that her kinetic energy is 320J?
  • 64 m/s
  • 8 m/s
  • 16 m/s
  • 4 m/s
Which one of the following possesses both kinetic and potential energies?
  • A man walking on the road
  • A man climbing a hill
  • A man lying on his bed
  • A man running in the garden.
A wound watch spring has ______ energy.
  • Mechanical
  • Kinetic
  • Potential
  • Kinetic and potential
If the speed of a motor car becomes six times, then the kinetic energy becomes
  • 6 times
  • 36 times
  • 12 times
  • 24 times
Asha lifts a doll from the floor and places it on a table. If the weight of the doll is known, what else does one need to know in order to calculate the work Asha has done on the doll?
  • the time required
  • the height of the table
  • the power she could deliver
  • cost of the doll or the table
The spring of the winding knob of a watch has
  • mechanical energy
  • only kinetic energy
  • only potential energy
  • kinetic or potential energy
You lift a suitcase from the floor and keep it on the table. The work done by you on the suitcase depends on
  • the path taken by the suitcase
  • your weight
  • the weight of the suitcase
  • the time taken by you in doing so
The work done in lifting 1 kg mass to a height of 9.8 m is about
  • 1 J
  • 9.8 J
  • $$(9.8)^2 J$$
  • $$\displaystyle \frac{1}{(9.8)^2} J$$
A car is moving at $$100\ km/h$$. If the mass of the car is $$950\ kg$$, Its kinetic energy is:
  • $$367\ MJ$$
  • $$0.367\ MJ$$
  • $$3.67\ MJ$$
  • $$3.67\ J$$
A girl weighing 50 kg makes a high jump of 1.2 m.What is her kinetic energy at the highest point? $${(g= 10 ms^{-2}}$$)
  • 6000 J
  • 600 J
  • 60 J
  • Zero
The kinetic energy of a body is increased by increasing its:
  • Mass
  • Weight
  • Velocity
  • Potential energy
The moon revolves around the earth because the earth exerts a radial force on the moon. Does  the earth perform work on the moon?
  • no
  • yes, sometimes
  • yes, always
  • cannot be decided
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