Energy and Work: Master the Fundamentals of Energy Transformations

Question 1

A car with a mass of 1000 kilograms is moving at a speed of 20 meters per second. What is the kinetic energy of the car?

Accepted Answer

100 kilojoules

Answer

10 kilojoules

Answer

1 kilojoule

Answer

1000 kilojoules

Question 2

Which of the following is NOT considered a form of energy?

Accepted Answer

Weight

Answer

Kinetic energy

Answer

Potential energy

Answer

Thermal energy

Question 3

Work done on an object is defined as the:

Accepted Answer

Force applied multiplied by the distance moved in its direction

Answer

Change in its kinetic energy

Answer

Change in its potential energy

Answer

Power applied multiplied by the time taken

Question 4

In a closed system, which of the following physical quantities is conserved?

Accepted Answer

Total energy

Answer

Total momentum

Answer

Total angular momentum

Answer

Total force

Question 5

Power, in the context of physics, is defined as:

Accepted Answer

Work done per unit time

Answer

Force applied per unit time

Answer

Energy released per unit time

Answer

Distance moved per unit time

Question 6

Which of the following best describes a non-conservative force?

Accepted Answer

Friction

Answer

Gravity

Answer

Spring force

Answer

Electrostatic force

Question 7

The potential energy stored in a stretched or compressed spring is given by:

Accepted Answer

1/2 kx^2

Answer

kx

Answer

kx^3

Answer

1/2 kx^4

Question 8

Which of the following is the standard international unit (SI unit) of energy?

Accepted Answer

Joule

Answer

Newton

Answer

Watt

Answer

Kelvin

Question 9

Which of the following is the SI unit of energy?

Accepted Answer

Joule

Answer

Newton

Answer

Watt

Answer

Coulomb

Question 10

Which of the following is not a form of potential energy?

Accepted Answer

Magnetic potential energy

Answer

Gravitational potential energy

Answer

Elastic potential energy

Answer

Chemical potential energy

Question 11

Which of the following is the SI unit of power?

Accepted Answer

Watt

Answer

Joule

Answer

Newton

Answer

Ampere

Question 12

A car engine produces 100 kW of power and travels 100 km in 1 hour. Calculate the work done by the engine.

Accepted Answer

360 MJ

Answer

100 kJ

Answer

1000 MJ

Question 13

Which of the following is the SI unit of energy?

Accepted Answer

Joule

Answer

Newton

Answer

Watt

Answer

Kelvin

Question 14

A ball is thrown vertically upward. At the highest point of its trajectory, which of the following is correct?

Accepted Answer

Potential energy is maximum, kinetic energy is zero

Answer

Kinetic energy is maximum, potential energy is zero

Answer

Both kinetic and potential energies are zero

Answer

Kinetic energy is zero, potential energy is maximum

Question 15

The law of conservation of energy states that:

Accepted Answer

Energy can be transformed from one form to another

Answer

Energy can be created or destroyed

Answer

Energy is always conserved

Answer

Energy is always lost in any process

Question 16

A projectile is launched straight up at 20 meters per second. Ignoring air resistance, what is the projectile's velocity at the highest point of its flight?

Accepted Answer

0 meters per second

Answer

10 meters per second

Answer

20 meters per second

Answer

40 meters per second

Question 17

Which option is NOT a recognized form of energy?

Accepted Answer

Displacement energy

Answer

Kinetic energy

Answer

Potential energy

Answer

Thermal energy

Question 18

Which equation calculates kinetic energy?

Accepted Answer

E = 1/2mv^2

Answer

E = mgh

Answer

E = Fd

Answer

E = Pt

Question 19

When a ball is thrown vertically upward and reaches its highest altitude, which of the following statements is true?

Accepted Answer

Potential energy is maximized while kinetic energy is zero.

Answer

Kinetic energy is maximized while potential energy is zero.

Answer

Both kinetic and potential energy are zero at this point.

Answer

Both kinetic and potential energy are at their maximum values.

Question 20

How is the efficiency of a machine defined?

Accepted Answer

Output energy divided by input energy

Answer

Input energy divided by output energy

Answer

Output energy minus input energy

Answer

Input energy plus output energy

Question 21

Which formula represents the kinetic energy of an object?

Accepted Answer

E = 1/2 mv^2

Answer

E = mgh

Answer

E = Fd

Answer

E = U/t

Question 22

An object is lifted vertically upward. At its highest point, it has:

Accepted Answer

Zero kinetic energy and maximum potential energy.

Answer

Maximum kinetic energy and zero potential energy.

Answer

Both zero kinetic and potential energy.

Answer

Both maximum kinetic and potential energy.

Question 23

Work is done on an object when a force:

Accepted Answer

Acts in the direction of the object's displacement.

Answer

Acts perpendicular to the object's displacement.

Answer

Acts opposite to the object's displacement.

Answer

Is applied to the object without causing displacement.

Question 24

Which unit is used to measure power?

Accepted Answer

Watt

Answer

Joule

Answer

Newton-meter

Answer

Kilogram

Question 25

A car accelerates from rest to a certain speed. If friction is ignored, which quantity remains constant?

Accepted Answer

Total mechanical energy

Answer

Kinetic energy

Answer

Potential energy

Answer

Work done on the car

Question 26

A spring is stretched by a certain distance. If the spring constant is doubled, how does the spring's potential energy change?

Accepted Answer

Increases by a factor of 4

Answer

Decreases by a factor of 2

Answer

Increases by a factor of 2

Answer

Decreases by a factor of 4

Question 27

An object is thrown vertically upward. At the highest point of its trajectory, its:

Accepted Answer

Kinetic energy is zero, and potential energy is maximum.

Answer

Kinetic energy is maximum, and potential energy is zero.

Answer

Both kinetic and potential energy are maximum.

Answer

Both kinetic and potential energy are zero.

Question 28

A pendulum swings back and forth. At the bottom of its swing, its:

Accepted Answer

Kinetic energy is maximum, and potential energy is zero.

Answer

Potential energy is maximum, and kinetic energy is zero.

Answer

Both potential and kinetic energy are zero.

Answer

Both potential and kinetic energy are maximum.

Question 29

The work done by a motor is:

Accepted Answer

The power output of the motor multiplied by the time of operation.

Answer

The change in kinetic energy of the system.

Answer

The change in potential energy of the system.

Answer

The sum of the kinetic and potential energy changes.

Question 30

In mechanical engineering, why is mechanical energy often not conserved in real-world applications?

Accepted Answer

Non-conservative forces, like friction and air resistance, cause energy loss.

Answer

Mechanical energy is always conserved in any system.

Answer

Mechanical energy is only conserved in closed systems without external influences.

Answer

Energy dissipation is a reversible process, allowing for the recovery of lost energy.

Question 31

Which of the following is NOT a unit of energy?

Accepted Answer

Newton-meter

Answer

Joule

Answer

Calorie

Answer

Kilowatt-hour

Question 32

A car of mass 1000 kg is moving with a speed of 20 m/s. If it is lifted to a height of 10 meters, what is its gravitational potential energy?

Accepted Answer

100 kJ

Answer

10 kJ

Answer

20 kJ

Answer

200 kJ

Question 33

The law of conservation of energy states that:

Accepted Answer

Total energy of an isolated system remains constant

Answer

Energy can be created or destroyed

Answer

Energy can only be transformed from one form to another

Answer

Energy is lost in every transformation

Question 34

The work done by a conservative force:

Accepted Answer

Is independent of the path taken

Answer

Depends on the path taken

Answer

Is always positive

Answer

Is always negative

Question 35

A ball is thrown vertically upward with an initial velocity of 10 m/s. What happens to its kinetic energy at the highest point of its trajectory?

Accepted Answer

It is converted entirely into potential energy.

Answer

It remains the same.

Answer

It is halved.

Answer

It is converted entirely into thermal energy.

Question 36

A 2 kg block slides down a frictionless plane inclined at an angle of 30° to the horizontal. If the block starts from rest, what is its speed at the bottom of the plane?

Accepted Answer

6.12 m/s

Answer

3.06 m/s

Answer

12.24 m/s

Answer

9.18 m/s

Question 37

Which of the following statements about energy is true?

Accepted Answer

Energy can be transformed from one form to another, but the total amount of energy in an isolated system remains constant.

Answer

Energy is a vector quantity.

Answer

Energy can be created or destroyed.

Answer

Energy can be lost due to friction, but it cannot be gained.

Question 38

Which of the following does NOT affect the gravitational potential energy of an object?

Accepted Answer

The speed of the object

Answer

The mass of the object

Answer

The gravitational field strength

Answer

The height of the object

Question 39

A pendulum swings back and forth. At the bottom of its swing, which type of energy is maximum and which type is minimum?

Accepted Answer

Kinetic energy is maximum, potential energy is minimum

Answer

Potential energy is maximum, kinetic energy is minimum

Answer

Both kinetic and potential energies are minimum

Answer

Both kinetic and potential energies are maximum

Question 40

Which of the following is a unit of energy?

Accepted Answer

Joule

Answer

Newton

Answer

Meter

Answer

Second

Question 41

A ball with mass **m** is dropped from a height **h**. Its potential energy at the moment of release is:

Accepted Answer

**mgh**

Answer

**hm/g**

Answer

**mg/h**

Answer

**m/gh**

Question 42

A constant force of **F** Newtons is applied to an object of mass **m** kilograms, causing it to move a distance of **d** meters. The work done by the force is:

Accepted Answer

**Fd**

Answer

**F/d**

Answer

**d/F**

Answer

**F²d**

Question 43

A car with mass **m** kilograms travels at a constant speed of **v** m/s. The power required to maintain this speed against a constant resistive force of **f** Newtons is:

Accepted Answer

**fv**

Answer

**f/v**

Answer

**v/f**

Answer

**f²v**

Question 44

A spring with a spring constant of **k** N/m is stretched a distance of **x** meters. The energy stored in the spring is:

Accepted Answer

**(1/2)kx²**

Answer

**k²x**

Answer

**x/k**

Answer

**kx**

Question 45

Which of the following is NOT a commonly used unit of energy?

Accepted Answer

**Newton**

Answer

**Calorie**

Answer

**Electronvolt**

Answer

**Joule**

Question 46

In a perfectly elastic collision, the total kinetic energy of the system:

Accepted Answer

Remains constant.

Answer

Is converted into potential energy.

Answer

Increases.

Answer

Decreases.

Question 47

A 10 kg object is lifted vertically 5 meters at a constant speed. What is the work done by the force of gravity on the object?

Accepted Answer

-490 J

Answer

490 J

Answer

0 J

Answer

98 J

Question 48

A ball is thrown vertically upward. At its highest point, what is the primary form of energy the ball possesses?

Accepted Answer

Gravitational potential energy

Answer

Chemical potential energy

Answer

Kinetic energy

Answer

Elastic potential energy

Question 49

A force of 10 N is applied to an object over a distance of 5 meters. The force is applied at an angle of 30 degrees to the direction of the object's displacement. What is the work done by this force?

Accepted Answer

43.3 J

Answer

25 J

Answer

50 J

Answer

86.6 J

Question 50

Which of the following forces is considered a non-conservative force?

Accepted Answer

Friction

Answer

Gravity

Answer

Electrostatic force

Answer

Spring force

Question 51

The work done by a conservative force is:

Accepted Answer

Independent of the path taken

Answer

Dependent on the path taken

Answer

Always positive

Answer

Always negative

Question 52

A roller coaster car starts from rest at the top of a hill and rolls down to the bottom. Which of the following best describes the energy transformations that occur, assuming minimal friction?

Accepted Answer

Potential energy is converted to kinetic energy.

Answer

Mechanical energy is not conserved due to friction.

Answer

Kinetic energy is converted to potential energy.

Answer

The total energy of the system increases.