Chapter-06: Work & Energy

 

After studying this unit, the students will be able to:

• Define work and its SI unit.
• Calculate word done using equation: Work = force x distance moved in the direction of force
• Define energy, kinetic energy and potential energy. State unit of energy.
• List the different forms of energy with examples.
• Describe the processes by which energy is converted from one form to another.
• State mass energy equation E-mc² and solve problems using it.
• Describe the process of electricity generation by drawing a block diagram of the process from fossil fuel input to electricity output.
• List the environmental issues associated with power generation.
• Explain by drawing energy flow diagrams through steady state systems such as filament lamp, power station, a vehicle travelling at a constant speed on a level road.
• Solve problems using mathematical relations learnt in this unit.

Multiple Choice Questions
1.	Product of force and distance covered in the direction of force is:
	a. Acceleration	b. Resistance
	c. Work	d. Specific heat
2.	For work _____ conditions should be fulfilled:
	a. 1	b. 2
	c. 3	d. 4
3.	Work is ______ quantity:
	a. Scalar	b. Vector
	c. Base	d. None of above
4.	Unit of work is:
	a. N	b. Nm
	c. J	d. Both b & c
5.	Work done will be ______ if no force act on the body:
	a. Maximum	b. Minimum
	c. Zero	d. All of above
6.	Work done will be maximum if displacement is ______ to force:
	a. Parallel	b. Perpendicular
	c. Tangent	d. Normal
7.	Work done will be zero if displacement is ______ to force:
	a. Parallel	b. Perpendicular
	c. Tangent	d. Normal
8.	Work done will be one _______ if a force of one Newton acts on the body and it covers the distance of 1 meter in the direction of force:
	a. Watt	b. Joule
	c. Newton	d. Coulomb
9.	One Mega joule is equal to:
	a. 106 J	b. 103 J
	c. 109 J	d. 102 J
10.	What will be the magnitude of work if a force of 25 N pulls a stone through a distance of 5 m in its direction:
	a. 25 J	b. 50 J
	c. 75 J	d. 125 J
11.	Which unit is equal to kgm2s-2 in the units given below:
	a. Joule	b. Newton
	c. Watt	d. Meter
12.	Rate of doing work with respect to time is known as:
	a. Energy	b. Power
	c. Momentum	d. None of above
13.	Unit of power is:
	a. Watt	b. Joule
	c. Newton	d. Coulomb
14.	How much power is used by a 40 kg athlete by climbing 10in high ladder in 10 s:
	a. 4 W	b. 40 W
	c. 400 W	d. 4000 W
15.	What will be the power of a machine doing 10 J work hi 5 seconds?
	a. 2 W	b. 10 W
	c. 25 W	d. 50 W
16.	Ability of a body to do work is known as:
	a. Force	b. Momentum
	c. Power	d. Energy
17.	There are ______ basic kinds of energy:
	a. 1	b. 2
	c. 3	d. 4
18.	Energy is ______ quantity:
	a. Vector	b. Scalar
	c. Base	d. None of above
19.	Unit of Energy in System International is:
	a. Watt	b. Joule
	c. Newton	d. Coulomb
20.	Energy possessed by a body due to its motion is called ______ energy:
	a. Kinetic	b. Potential
	c. Mechanical	d. All of above
21.	A bowler during playing cricket throws a ball of mass 200 g with a velocity of 20 ms1.
	a. 4 J	b. 40 J
	c. 400 J	d. 4000 J
22.	What will be the kinetic energy of a body if its velocity is doubled?
	a. Doubled	b. Four times
	c. Eight times	d. Half
23.	What will be the kinetic energy of a body if its mass is doubled?
	a. Doubled	b. Four times
	c. Eight times	d. Half
24.	What will be the kinetic energy of a car of mass 1000 kg moving with a velocity of 20 ms-1?
	a. 2 x102 J	b. 2 x103 J
	c. 2 x105 J	d. 2 x107 J
25.	Ability of a body to do work due to its position is called _____ energy:
	a. Kinetic	b. Potential
	c. Mechanical	d. All of above
26.	Ability of a body to do work due to its height from the surface of earth is called _____ energy:
	a. Gravitational Potential	b. Elastic Potential
	c. Chemical Potential	d. Attraction
27.	When a ball is lifted to a height ‘h’ from the ground, it will posses ______ energy:
	a. Kinetic	b. Gravitational potential
	c. Elastic potential	d. Mechanical
28.	Total energy of the system:
	a. Increases	b. Decreases
	c. Remains same	d. All of above
29.	For movement of our body _____ energy is used:
	a. Heat	b. Electrical
	c. Chemical	d. Mechanical
30.	1 hp =
	a. 726 W	b. 736 W
	c. 746 W	d. 756 W
31.	For the propagation of signals in our body ______ energy is used:
	a. Heat	b. Electrical
	c. Chemical	d. Mechanical
32.	For maintaining the body temperature _____ energy is used:
	a. Heat	b. Electrical
	c. Chemical	d. Mechanical
33.	Increase in K.E is equal to:
	a. Increase in P.E	b. Decrease in P.E
	c. No effect	d. Both a & b
34.	Increase in P.E is equal to:
	a. Increase in K.E	b. Decrease in K.E
	c. No effect	d. Both a & b
35.	Decrease in K.E is equal to:
	a. Increase in P.E	b. Decrease in P.E
	c. No effect	d. Both a & b
36.	Decrease in P.E is equal to:
	a. Increase in K.E	b. Decrease in K.E
	c. No effect	d. Both a & b
37.	A motor lift a w eight of 5N up to the height of 2m in 4s. What will be the power of the motor?
	a. 2.5 W	b. 5 W
	c. 20 W	d. 10 W
38.	Energy of the water stored in the dam is:
	a. Elastic potential energy	a. Gravitational potential energy
	c. Kinetic energy	b. Mechanical energy
39.	How many types of mechanical energy are?
	a. 1	b. 2
	c. 3	d. 4

Online Taleem provides students good notes in your study that helps you to quickly review the key points in the material that you have read and clear your concept is an important part of academic success in school / college. It is also an effective learning strategy that intentionally identifying the important content for your desire course and professional practice. This will also help you in improving your comprehension of material and retention.