CBSE Questions for Class 11 Engineering Physics Work,Energy And Power Quiz 5 - MCQExams.com

(i) What is the work done by the porter when he climbs up a height of 10 m $$\displaystyle (g\quad = 10\ {ms} ^{-2})$$? 
  • $$5kJ^2$$
  • $$50kJ$$
  • $$100kJ^2$$
  • $$5kJ$$
A ball moving with a velocity v strikes a wall moving toward the ball with a velocity u. An elastic impact lasts for t sec. Then the mean elastic force acting on the ball is 
  • $$\displaystyle \frac { 2mv }{ t } $$
  • $$\displaystyle \frac { 2m\left( \upsilon +u \right) }{ t } $$
  • $$\displaystyle \frac { 2m\left( \upsilon +2u \right) }{ t } $$
  • $$\displaystyle \frac { m\left( 2\upsilon +u \right) }{ t } $$
Two bodies of equal weight are kept at heights of h and 1.5 h respectively. The ratio of their P.E. will be :
  • 3: 2
  • 2: 3
  • 1: 1
  • none of these
An object of mass $$1  kg$$ has a P.E. of $$1  J$$ relative to the ground when it is at a height of
  • $$0.1 m$$
  • $$1 m$$
  • $$9.8 m$$
  • $$32 m$$
A body rolling down a hill has :
  • K.E. only
  • P.E. only
  • neither K.E. nor P.E.
  • both K.E. and P.E
A raised hammer possesses :
  • K.E. 
  • P.E.
  • electrical energy
  • sound energy
The energy directly related to the speed of a moving body and its mass is:
  • kinetic
  • potential
  • solar
  • electric
A heavy object has .......  gravitational potential energy than a lighter one.
  • less
  • more
  • same
  • none of these
The relationship between force and position is shown in the figure (in one dimensional case). Work done by the force in displacing a body from 
$$ X=1\  cm\  to\ $$$$X=5\  cm\  is$$:

371097.jpg
  • 700 ergs
  • 70 ergs
  • 60 ergs
  • 20 ergs
The mass of an object $$P$$ is double the mass of $$Q$$. If both move with the same velocity, then the ratio of K.E. of $$P$$ to $$Q$$ is
  • 1 : 2
  • 2 : 1
  • 1 : 4
  • 4 : 1
Which one of the following types of energy is possessed by a body when placed at a certain height?
  • Kinetic energy
  • Potential energy
  • Heat energy
  • Sound energy
  • None of these
Find the potential energy if a body is placed at a certain height of 5 m from the earth.
412338.jpg
  • 196 J
  • 200 J
  • 150 J
  • 300 J
  • None of these
The water stored in a reservoir possesses :
  • Kinetic energy
  • Muscular energy
  • Potential energy
  • Magnetic energy
Kinetic energy of a body depends on its:
  • Position
  • Velocity
  • Shape
  • Colour
When an aeroplane takes off from the ground :
  • Kinetic energy increases and Potential energy decreases
  • Potential energy increases and Kinetic energy remains constant
  • Both Kinetic energy and Potential energy remain constant
  • Both Kinetic energy and Potential energy increase
Which of the following does not have potential energy ?
  • An inflated balloon
  • Water in a flowing river
  • A fruit on the tree
  • A spinning top
A stone tied to a string is rotated in a vertical plane. If mass of the stone is $$m$$, the length of the string is $$r$$ and the linear speed of the stone is $$v$$,When the stone is at its lowest point, then the tension in the string will be :
  • $$\displaystyle \frac { m{ v }^{ 2 } }{ r } +mg$$
  • $$\displaystyle \frac { m{ v }^{ 2 } }{ r } -mg$$
  • $$\displaystyle \frac { mv }{ r } $$
  • $$\displaystyle mg$$
A crane pulls up a car of mass $$500kg$$ to a vertical height of $$4m$$. So, work done by the crane is:
  • $$19.6J$$
  • $$19.6kJ$$
  • $$19600kJ$$
  • $$4900J$$
A boy of mass $$40\ kg$$ runs up a flight of $$50$$ steps, each $$10\ cm$$ high in $$14\ s$$. So, work done by the boy is:
  • $$1960\ J$$
  • $$19.6\ J$$
  • $$980\ J$$
  • $$9.8\ J$$
A fruit hanging from the top branch of a tree possesses
  • gravitational potential energy
  • elastic potential energy
  • kinetic energy
  • sound energy
A body of mass $$6kg$$ is acted upon by a force which causes a displacement in it given by $$x=\cfrac{{t}^{2}}{4}$$ metre, where $$t$$ is the time in second. The work done by the force in $$2s$$ is
  • $$12J$$
  • $$9J$$
  • $$6J$$
  • $$3J$$
In which form, the energy is stored in a fuel?
  • Potential energy
  • Thermal energy
  • Kinetic energy
  • Chemical energy
A string of length $$L$$ and force constant $$K$$ is stretched to obtain extension $$l$$. It is further stretched to obtain extension $${l}_{1}$$. The work done in second stretching is
  • $$\dfrac{1}{2}K{l}_{1}\left(2l+{l}_{1}\right)$$
  • $$\dfrac{1}{2}K{l}_{1}^{2}$$
  • $$\dfrac{1}{2}K\left({l}^{2}+{l}_{1}^{2}\right)$$
  • $$\dfrac{1}{2}K\left({l}_{1}^{2}-{l}^{2}\right)$$
An object of mass $$40\ kg$$ is raised to a height of $$5\ m$$ above ground. If the object is allowed to fall down find its kinetic energy when it is half-way down.
  • 1960 J
  • 980 J
  • 990 J
  • 1000 J
Which one of the following energies cannot be possessed by a body at rest?
  • Potential energy
  • Kinetic energy
  • Thermal energy
  • Magnetic energy
If the string were to break at point II, what would be the path of the ball?
485593_b6c13b64e3094f35845dd994f15ac3dc.png
  • None of these
Which of the following statements is true?
485590_be3171b356084855bdbe0f0c72be3059.png
  • The tension in the string is greater at points III than at point I
  • The tension in the string is greater at points I than at point III
  • The tension at point I is equal to the tension at point III
  • The tension in the string is greatest at point II
  • The tension in the string is same at points I, II and III
A ball of mass $$m$$ is attached with the string of length $$R$$, rotating in circular motion, with instantaneous velocity $$v$$ and centripetal acceleration $$a$$.
Calculate the centripetal acceleration of the ball if the length of the string is doubled?
  • $${a}/{4}$$
  • $${a}/{2}$$
  • $$a$$
  • $$2a$$
  • $$4a$$
A car standing at the top of a hill would be an example of what type of energy?
  • Kinetic
  • Topical
  • Potential
  • Beneficial
  • Residual
A $$110 kg$$ panda is riding on a $$3.0 m$$ long swing whose mass can be considered negligible. The highest point of its arc occurs when the swing makes a $${20}^{o}$$ angle with the vertical.
What is the magnitude of the total tension in the ropes of the swing at that point?
495418.jpg
  • $$0N$$
  • $$103 N$$
  • $$369 N$$
  • $$1013 N$$
  • $$1078 N$$
The position function of a particle is given by $$x\left(t\right)=k{t}^{{5}/{2}}$$, where $$k$$ is a constant.
If the particle starts at rest and is propelled through some distance $$d$$ so that the trajectory matches $$x\left(t\right)$$, the work done on the particle is proportional to which power of $$t$$?
  • $${t}^{5}$$
  • $${t}^{3}$$
  • $${t}^{{5}/{2}}$$
  • $${t}^{{3}/{2}}$$
  • Not enough information
A stone ties to a rope is rotated in a vertical circle with uniform speed. If the difference between the maximum and minimum tension in the rope is $$20\  N$$, mass of the stone in $$kg$$ is:
 ($$\displaystyle g=10{ ms }^{ -2 }$$)
  • $$1.0$$
  • $$1.5$$
  • $$0.5$$
  • $$0.75$$
In vertical circular motion, the ratio of kinetic energy to potential energy at the horizontal position is ____________.
  • $$5:2$$
  • $$2:1$$
  • $$3:2$$
  • $$2:3$$
A $$50 kg$$ acrobat is swinging on a rope with a length of $$15 m$$ from one horizontal platform to another. Both platforms are at equal height.
If the maximum tension the rope can support is $$1200 N$$, which of the following answer best represents the maximum velocity the acrobat can reach without breaking the rope?
  • $$25 {m}/{s}$$
  • $$19 {m}/{s}$$
  • $$20 {m}/{s}$$
  • $$15 {m}/{s}$$
  • $$5 {m}/{s}$$
Under the action of a force $$F=Cx$$, the position of a body changes from $$0$$ to $$x$$. The work done is :
  • $$\cfrac { 1 }{ 2 } C{ x }^{ 2 }$$
  • $$C{ x }^{ 2 }$$
  • $$Cx$$
  • $$\cfrac { 1 }{ 2 } C{ x }$$
Calculate the work done in moving a cart from $$x=a$$ to $$x=b$$ whose mass is $$3kg$$ and the given surface is frictionless. $$(Take\ g=9.8m/s^{2})$$
  • $$0$$
  • $$3g(a-b)$$
  • $$3g$$
  • $$3g(a+b)$$
Fifteen joules of work is done on object A, which is attached to an uncompressed spring, so that all the work done goes into compressing the spring.
Sixty joules of work is done on object B, which is attached to an uncompressed spring that is identical to the spring to which object A is attached; all the work done goes into compressing the spring.
How does the compression of the spring for object B compare to the compression of the spring for object A after this work is done?
  • The compression of the spring for object B is four times as much as it is for object A
  • The compression of the spring for object B is sixteen times as much as it is for object A
  • The compression of the spring for object B is two times as much as it is for object A
  • The compression of the spring for object B is less than two times as much as it is for object A (but not the same amount)
  • The compression of the spring for object B is the same as it is for object A
A simple pendulum of length $$L$$ carries a bob of mass $$m$$. When the bob is at its lowest position, it is given the minimum horizontal speed necessary for it to move in a vertical in circle about the point of suspension. When the string is horizontal the net force on the bob is
  • $$\sqrt {10}mg$$
  • $$\sqrt {5}mg$$
  • $$4 mg$$
  • $$1 mg$$
The correct formula to find the velocity of a body with kinetic energy '$$k$$' is:
  • $$V=\dfrac{2k}{m}$$
  • $$V=\sqrt{\dfrac{2k}{m}}$$
  • $$V=\dfrac{4{k}^{2}}{m}$$
  • $$V=\dfrac{1}{2}km$$
Kinetic energy of a body depends upon its:
  • mass
  • velocity
  • density 
  • both A and B
A body is acted upon by a force which is proportional to the distance covered. If distance covered by denoted by x, then work done by the force will be proportional to:
  • $$x$$
  • $$x^2$$
  • $$x^{\dfrac{3}{2}}$$
  • $$x^4$$
A small stone tied to an inextensible string of negligible mass is rotated in a circle of radius $$2 m$$ in a vertical plane. Find the speed at a horizontal point on the circle. (in $$m/s$$)
  • $$7.67$$
  • $$2.36$$
  • $$6.32$$
  • $$8.32$$
A stone of mass $$10 kg$$ tied with a string of length $$0.5 m$$ is rotated in a vertical circle. Find the total energy of the stone at the highest position. (in $$J$$)
  • $$123.36$$
  • $$122.5$$
  • $$154.3$$
  • $$185.6$$
A $$2kg$$ object is moving at $$3m/s$$. A $$4N$$ force is applied in the direction of motion and then removed after the object has travelled an additional $$5m$$. The work done by this force is:
  • $$10 J$$
  • $$15 J$$
  • $$20 J$$
  • $$25 J$$
A $$200 g$$ mass is whirled in a vertical circle making $$60$$ revolutions per minute. What is the tension in the string at the top of the circle if the radius of the circle is $$0.8 m$$? (in $$N$$)
  • $$6.3$$
  • $$2.36$$
  • $$4.35$$
  • $$4.23$$
A force of $$10 N$$ is applied on a object of mass $$1 kg$$ for $$2 s$$, which was initially at rest. What is the work done on the object by the force?
  • $$200 J$$
  • $$20 J$$
  • $$16 J$$
  • $$180 J$$
A $$500 g$$ particle tied to one end of a string is whirled in a vertical circle of circumference $$14 m$$.If the tension at the highest point of its path is $$2 N$$, what is its speed? (in m/s)
  • $$4.365$$
  • $$5.369$$
  • $$5.546$$
  • $$4.331$$
Two wires are stretched through same distance. The force constant of second wire is half as that of the first wire. The ratio of work done to stretch first wire and second wire will be
  • $$2 : 1$$
  • $$1 : 2$$
  • $$3 : 1$$
  • $$1 : 3$$
Two springs have their force constant as $$k_1$$ and $$k_2(k_1 > k_2)$$. When, they are stretched by the same force, then, 

681162_e0f54ede9e3f4cfca4cf50a90f3824e2.PNG
  • More work is done in case of first spring
  • Less work is done in case of first spring
  • More work is done in case of second spring
  • Loss work is done in case of second spring
The work done in joules in increasing the extension of a spring of stiffness $$10\ N/cm$$ from $$4\ cm$$ to $$6\ cm$$.
  • $$1$$
  • $$10$$
  • $$50$$
  • $$100$$
0:0:1


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