Work And Energy Test

Result

Work And Energy Test - 2

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Weekly Quiz Competition

Question 1
1 / -0

Calculate the work done in lifting 100 kg of water through a vertical height of 3 meter. (Assuming g = 10 m/s²)

A
4000 J

B
12000 J

C
3000 J

D
300 J

Solution

Vertical height (Displacement) (d) = 3 metre

Mass of water (m) = 100 kg

Acceleration (a) = g = 10 m/s²

Work done = F × d

W = m × a × d

W = 100 × 10 × 3

W = 3000 Nm = 3000 J ( 1 Nm = 1 J)
Question 2
1 / -0

A dry cell converts one form of energy into another.Which of the following options depicts the two forms?

A
Chemical energy into electrical energy.

B
Electrical energy into chemical energy

C
Solar energy into chemical energy

D
Solar energy into electrical energy

Solution

A dry cell converts chemical energy into electrical energy.
Question 3
1 / -0

Which of the following statements is not true?

A
At thermal power station, chemical energy of coal is changed into heat energy, which is further changed into electrical energy.

B
One form of energy can be transformed into another.

C
Different forms of energy can be measured in different units.

D
Energy and work done have the same units.

Solution

All forms of energy have the same units.
Question 4
1 / -0

Which of the following physical quantities has its units Watt?

A
Energy

B
Power

C
Force

D
None of these

Solution

Power = work done / time

Power = J/s = 1 Watt (Because 1 J/s = 1 Watt)
Question 5
1 / -0

Which of the following options is correct?

A
1 watt = 1 Joule × 1second

B
1 watt = 1 Joule per second

C
1 watt × 1 Joule = 1 second

D
1 watt × 1 Joule × 1 second = 1

Solution

Power = work done / time

Power = J/s = 1 Watt (Because 1 J/s = 1 Watt)
Question 6
1 / -0

How much work is done when a force of 2 N moves a body through a distance of 10 cm in the direction of force?

A
200 J

B
0.02 J

C
0.2 J

D
20 J

Solution

Displacement (d) = 10 cm = 0.1 m (Because 1 cm = 0.01 m)

Force (F) = 2 N

Work done = F × d

W = 2 × 0.1m

W = 0.2 Nm = 0.2 J (1 Nm = 1 J)
Question 7
1 / -0

A ball of mass 200 g falls from a height of 5 m. What is its kinetic energy, when it just reaches the ground? (g = 9.8 m/sec²)

A
9.8 J

B
980 J

C
4.9 J

D
None of these

Solution

Mass of the ball (m) = 200 g = 0.2 kg (Because 1g = 0.001 kg)
Height h = 5 m
Initial velocity, u = 0
We know that,
v²- u² = 2gs
v² - 0 = 2 × 9.8 × 5
v² = 98
Kinetic energy = ½ × m × v²
= ½ × 0.2 × 98 = 9.8 Joule
Question 8
1 / -0

Two bodies A and B of equal masses are kept at height of h and 2h respectively. What will be the ratio of their potential energies?

A
1: 2

B
2: 1

C
4: 1

D
1: 4

Solution

Mass of body = m₁ = m Height of m₁ = h

Mass of body = m₂ = m Height of m₂ = 2h

Ratio of potential energy = P₁/ P₂= m₁gh/m₂g (2h)= mgh/2mgh= 1/2

Therefore, P₁ : P₂ = 1 : 2
Question 9
1 / -0

What is the power of an engine which is capable of doing 10,000 J of work in 10 minutes?

A
1,000 W

B
166 W

C
16.6 W

D
60,000 W

Solution

Work done = 10,000 J

Time = 10 minutes = 10 × 60 sec = 600 s (Because 1 minute = 60 seconds)

Power = Work done/Time = 10,000/600 = 16.6 Watt
Question 10
1 / -0

When we compress a coil spring, the elastic potential energy

A
increases

B
decreases

C
disappears

D
remains unchanged

Solution

When a coil spring is compressed, the elastic potential energy is increased.

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Re-Attempt Weekly Quiz Competition

Work And Energy Test - 2

Result

Work And Energy Test - 2

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SHARING IS CARING

Question 1

4000 J

12000 J

3000 J

300 J

Solution

Question 2

Chemical energy into electrical energy.

Electrical energy into chemical energy

Solar energy into chemical energy

Solar energy into electrical energy

Solution

Question 3

At thermal power station, chemical energy of coal is changed into heat energy, which is further changed into electrical energy.

One form of energy can be transformed into another.

Different forms of energy can be measured in different units.

Energy and work done have the same units.

Solution

Question 4

Energy

Power

Force

None of these

Solution

Question 5

1 watt = 1 Joule × 1second

1 watt = 1 Joule per second

1 watt × 1 Joule = 1 second

1 watt × 1 Joule × 1 second = 1

Solution

Question 6

200 J

0.02 J

0.2 J

20 J

Solution

Question 7

9.8 J

980 J

4.9 J

None of these

Solution

Question 8

1: 2

2: 1

4: 1

1: 4

Solution

Question 9

1,000 W

166 W

16.6 W

60,000 W

Solution

Question 10

increases

decreases

disappears

remains unchanged

Solution

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