Work and Energy, Formula of Work, Unit of Work, What is Energy, Unit of Power Online Preparation Sample Paper Questions with Answer
Prepare for the ECAT Physics section with a comprehensive set of Physics Work and Energy MCQs at Nokryan.com. This is an essential aspect of learning the basics of mechanics, energy transfer, and power calculations. The content is well-organized and ensures conceptual understanding is clear, which is essential for students preparing for the ECAT Entry Test.
Understanding Work and Energy
Work and energy are two related concepts in physics. We say that work is done when a force acts on an object and causes a displacement in the direction of the force. In Mathematical form, this is written as:
Work (W) = Force (F) × Displacement (d) × cos(θ)
θ is the angle between the force and the displacement. Work is measured in Joules (J), the SI unit for energy.
Energy, on the other hand, is the capacity to do work. These exist in various forms, including kinetic energy, potential energy, thermal energy, and electrical energy, among others. The Work-Energy Principle states that the work done on an object = Change in the kinetic energy of the object:
W = ΔKE = ½ m (Vf² – Vi²)
where m is mass, Vf is final velocity, and Vi is initial velocity.
Formula of Work and Unit of Work
The basic equation for work involves at least force, displacement, and angle of application. In SI, the unit of work is the Joule, such that:
1 Joule = 1 Newton × 1 meter (1 J = 1 N·m)
This unit signifies that work is done when the force of one Newton moves an object by one meter in the force’s direction.
What is Energy? Types and SI Units
Energy is categorized into different types, including:
- Kinetic energy (KE): Energy of motion, expressed as KE = ½ mv²
- Potential Energy (PE): stored energy from position PE = mgh
- Mechanical Energy: The sum of the kinetic and potential energy of a system
- Thermal and Electrical Energy: Related to heat and electricity
The SI unit of energy, like work, is also the Joule (J).
Power and Its Unit
Power refers to the rate of doing work or energy transfer per unit of time. It is given by:
P = W/t
where W is work and t is time. The SI unit of power is the Watt (W):
1 Watt = 1 Joule/second (1 W = 1 J/s)
In both mechanical and electrical applications, transferring energy faster is paramount for higher power.
Entry Test Physics Work and Energy MCQS Online Preparation Sample Paper 1 Questions with Answer
1. The SI unit of power is
- None of these
- Joule
- Pound
- Watt correct
2. Work is defined as the dot product force and displacement which is a?
- Vector quantity
- Constant quantity
- None of these
- Scalar quantity correct
3. Power is defined as?
- P = mV/t
- P = ∆W/Vt correct
- P = mt/V
- P = ∆V/∆t
4. The magnitude of work is?
- W = Fd
- W = df cos Ѳ
- W = Fd cos Ѳ
- None of these correct
5. The field in which the work done be independent of the path followed is called?
- Conservative fields correct
- Non-conservative field
- None of these
- Varying intensity field
6. Power can also be defined as?
- P = F . W
- None of these
- P = F . A
- P = →F. →V correct
7. An average energy used to make a car is?
- 7 x 10⁸ J
- 4 x 10⁷ J
- 8 x 10⁹ J
- 9 x 10⁹ J correct
8. Which type of the following force cannot do work, acting on a body
- Frictional force
- Gravitational force
- Centripetal force
- Electric force correct
9. A 70 kg man runs up a long height of stairs in 4.0 se. The vertical height of the stairs is 4.5 m. Calculate its power output in watts
- 7.2 x 10² W
- 7.3 x 10² W
- 7.7 x 10² W correct
- 7.1 x 10³ W
10. Work done by a body when it covers some distance in suitable direction, may be?
- All of these correct
- Negative
- Positive
- Zero
11. SI unit of work is?
- N-ms¯²
- N-m²
- N-ms¯¹
- N-m correct
12. Approximate power of colour T.V. in watt is?
- 120 correct
- 90
- 100
- 130
13. The work done by the body is maximum when it has angle
- 0⁰ correct
- 90⁰
- 30⁰
- 60⁰
14. Kilowatt-hour is a unit of?
- None of these
- Electrical Energy correct
- Power
- Energy
15. One kilowatt hour is equal
- 3.6 x 10⁶ J correct
- 3.5 x 10⁶ J
- 3.6 x 10⁸ J
- 3.5 x 10⁵ J
16. No work is done by the body when angle between force and displacement is?
- 60⁰
- 45⁰
- 0⁰
- 90⁰ correct
17. The dimensions of work are
- ML²T¯² correct
- MLT¯²
- ML³T¯²
- MLT¯¹
18. Which of the following is conservative filed
- Electrostatic field correct
- Viscous field
- Frictional field
- All of these
19. Which of the following is non-conservative field?
- Frictional field correct
- Electrostatic field
- None of these
- Gravitational fields
20. Work done is a gravitational field along a closed loop is?
- Minimum
- Maximum
- 1
- Zero correct
Entry Test Physics Work and Energy MCQS Online Preparation Sample Paper 2 Questions with Answer
1. Approximate power of a pocket calculator in watts
- 7.5 x 10²
- 7.5 x 10¯⁴ correct
- 7.5 x 10¯²
- 7.5 x 10¯⁵
2. The escape velocity of Uranus in Kms¯¹
- 24.09
- 23.07
- 22.4 correct
- 24.5
3. Approximate power of an electric heater in watts
- 2 x 10⁸
- 2 x 10⁵
- 2.1 x 10⁴
- 2 x 10³ correct
4. An average energy used by the car-from petrol in its life time
- 1 x 10¹⁰ J
- 1 x 10⁹ J
- 1 x 10¹¹ J
- 1 x 10¹² J correct
5. The total work done in displacing a body from the surface of earth to infinite point is?
- W total = GMm/r₁
- W total = – GMm/ r₁ correct
- W total = Gm/ r₁
- W total = GMm/ r₁²
6. The escape velocity of mercury in Kms¯¹
- 4.3 correct
- 1.29
- 4.02
- 3.24
7. The escape velocity of Neptune in Kms¯¹
- 20.26
- 25.4 correct
- 25.6
- 24.03
8. Approximate power of Jumbo. Let Aircraft in watts
- 1.2 x 10⁸
- 1.3 x 10⁸ correct
- 1.2 x 10⁶
- 1.1 x 10⁹
9. The escape velocity Venus in Kms¯¹
- 8.24
- 10.4 correct
- 5.28
- 10.02
10. Approximate power of flash light in watts: (2 cells)
- 1.56
- 1.5 correct
- 1.55
- 1.2
11. The relation for the work energy principle is?
- None of these
- Vx² – Vy² = Fd
- ½ m Vy – ½ mvx = Fd
- 1/2mVf² – ½mVi² = Fd correct
12. All the food you eat in one day has the energy equivalent to petrol of?
- 1/5 liter
- 1/8 liter
- 1/3 liter correct
- 1/6 liter
13. The escape velocity of the moon in Kms¯¹ is
- 1.23
- 2.59
- 2.40 correct
- 2.43
14. The escape velocity of Mars in Kms¯¹
- 5.23
- 2.89
- 3.99
- 5.00 correct
15. Work energy principle is the work done on the body is equal to
- Change in acceleration
- Change in K.E correct
- Change in power
- Change in angular velocity
16. The energy due to all the fossil fuels on the Earth is so small that, the energy reaching Earth in just days of sunlight which is?
- 30 days
- 10 days correct
- 5 days
- 60 days
17. Approximate power of a car moving at a speed of 90 kmh¯¹ in watts
- 1.4 x 10⁸
- 1.3 x 10⁷
- 1.2 x 10⁶
- 1.1 x 10⁵ correct
18. The escape velocity of Earth in Kms¯¹
- 9.75
- 11.2 correct
- 15.6
- 12.3
19. The absolute gravitational potential energy of a body at a distance ‘r’ from the centre of the Earth
- U = GMm/ r²
- U = – GMm/r correct
- U = GMm/r
- None of these
20. The escape velocity of Saturn in Kms¯¹
- 37.4
- 37.0 correct
- 30.0
- 35.04
Entry Test Physics Work and Energy MCQS Online Preparation Sample Paper 3 Questions with Answer
1. The renewable energy source is
- Biomass correct
- Tides
- None of these
- Natural gas
2. The initial velocity with which a body projected upward and never comes back is called?
- None of these
- Escape velocity correct
- Terminal velocity
- Kinetic energy
3. The average velocity of Jupiter in Kms¯¹
- 25
- 61.0 correct
- 58.4
- 50
4. The relation for the escape velocity is?
- V esc = √2gR correct
- V esc = √2G/g
- V esc= √2GM/R₂
- V esc = √GM/R
5. The original source of tides is
- Ocean
- Earth
- Moon correct
- Sun
6. The tides are produced in the sea due to force which is?
- Gravitational force of moon correct
- Combined effect of both forces
- None of these
- Electromagnetic force of the moon
7. The original source of biomass energy is
- None of these
- Moon
- Geothermal
- Sun correct
8. The moon produce tidal effect in the sea by pulling
- Both correct
- None of these
- The sea
- The land
9. The original source of fossil fuels is?
- Biomass
- Geothermal
- None of these
- Sun correct
10. The nonrenewable energy source is
- Uranium correct
- Hydroelectric
- None of these
- Sunlight
11. The original source of solar energy is
- Stars
- Sun correct
- Earth
- Moon
12. When a body falls, its height decreases also its potential energy decreases. The expression is?
- h₁ – h₂ = 1/2 m ( V₁² – V₂²)
- mg(h₁ – h₂) = 1/2 m (V₂² – V₁²) correct
- mg(h₂ – h₁) = 1/2 m ( V₁² – V₂²)
- mg(h₁² – h₂²) = 1/2 m ( V₂² – V₁²)
13. The original source of hydroelectric is
- Water correct
- Sun
- Sind
- Moon
14. The original source of wind energy is
- Tides
- Waves correct
- Sun
- Moon
15. The original source of geothermal energy is
- Fossil fuels
- Biomass
- Moon
- Earth correct
16. The original source of waves is
- Wind
- None of these
- Sun correct
- Moon
17. The moon produces the raise of the water in the sea roughly
- Twice a day correct
- Once a day
- None of these
- Several a day
18. Salter’s duck consists of?
- Balance float
- Body float
- A and C correct
- Duck float
19. By the pull of the moon, the land up and down by as much as
- 10 cm
- 12 cm
- 16 cm
- 25 cm correct
20. If it is assumed that a frictional force f is present, during the downward motion their?
- None of these
- mgh – f = ½ m²v
- mgh – f ½ mv² correct
- 2mgh – f = ½ mv²
Importance of Work and Energy in ECAT Physics
Work and energy principles play a significant role in physics applications, from mechanical systems to electrical power calculations. Understanding their formulas, SI units, and principles ensures a solid foundation for the ECAT Physics Entry Test.
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