Work and Energy Test

Result

Work and Energy Test - 22

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

A 220 V, 100 W bulb is connected to a 110 V source. Calculate the power consumed by the bulb.

A
10 W

B
15 W

C
20 W

D
25 W

Solution

$$P=100W$$
$$V=220V$$
We know
$$P=\dfrac{V^2}{R}$$
So
$$R=\dfrac{V^2}{P}$$=$$\dfrac{220^2}{100}$$=$$484\Omega$$

Supply=$$V=110V$$
$$P=\dfrac{V^2}{R}$$
$$P=\dfrac{110^2}{484}$$=$$25W$$
Question 2
1 / -0

A girl of mass 40 kg climbs 50 stairs of average height 20 cm each in 50 s. Find the power of the girl. $$(g = 10 m\:s^{-2})$$

A
$$50\ W$$

B
$$20\: W$$

C
$$80\ W$$

D
$$500\: W$$

Solution
Question 3
1 / -0

If an electric iron of $$1200 \ W$$ is used for $$30 \ minutes$$ everyday, find electric energy consumed in the month of April.

A
$$12\ kWh$$

B
$$18 \ kWh$$

C
$$36\ kWh$$

D
$$6\ kWh$$

Solution

$$Power \ \ P= 1200 W = \dfrac{1200}{1000}=1.2 kW$$

$$time \ \ t = 30 \ min =\dfrac{30}{60}=0.5 h$$

Number of days in the month of april = $$30$$
Hence, Total time for which iron is used is given by (in hrs) = $$ 0.5 \times 30$$

$$Energy \ \ E =Power\times Total \ time$$
$$= 1.2\times 0.5\times 30$$
$$= 18 kW h$$
Question 4
1 / -0

Answer question numbers 72 and 73 based on the following information.
Solar surface radiates energy uniformly at a rate of $$4 \times 10^{26}W$$. This energy spreads or distributes uniformly and normally outwards.

72. Considering Earth and the Sun to be spherical object, the amount of radiant energy received by the Earth per second is nearly

A
$$1360 \:W.$$

B
$$1.75 \times 10^{17}\:W$$

C
$$3.5 \times 10^{17}\:W$$

D
$$7 \times 10^{17}\:W$$
Question 5
1 / -0

A girl having a mass of $$35\ kg$$ sits on a trolley of mass $$5\ kg$$. The trolley is given an initial velocity of $$4\ ms^{-1}$$ by applying a force. The trolley comes to rest after traversing a distance of $$16\ m$$. How much work is done on the trolley?

A
$$0\ J$$

B
$$320\ J$$

C
$$120\ J$$

D
$$250\ J$$

Solution

Given,
Mass of the girl, $$m_g=35\ kg$$
Mass of the trolley, $$m_t=5\ kg$$
Iniial velociy, $$u=4\ ms^{-1}$$
Final velocity, $$v=0$$
Displacement, $$s=16\ m$$
Total mass, $$m=m_g+m_t$$
$$m=35+5 =40\ kg$$

Using Newton's second equation of motion,
$$s=ut+\dfrac 12u^2$$

$$\implies a=\dfrac{v^{2}-u^{2}}{2s}$$

$$a=-\dfrac{0^2-4^2}{2\times 16}$$

$$a=-0.5\ ms^{-2}$$

Force, $$F=ma$$
$$F=40\times (-0.5)$$
$$F=-20\ N$$
Magnitude of force, $$F=20\ N$$

Work done on the trolley, $$W= (20 \times 16)\ J$$
$$W= 320\ J$$
Question 6
1 / -0

In a hydro power plant:

A
Potential energy possessed by stored water is converted into electricity

B
Kinetic energy possessed by stored water is converted into potential energy

C
Water is heated to produce electricity

D
Water is converted into steam to produce electricity

Solution

Hydro power plant uses the potential energy stored in water. When water flows down the dam, potential energy is converted into kinetic energy which is used to rotate the turbine which produce electricity.
Question 7
1 / -0

Directions For Questions

Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.

...view full instructions

How much work they do in just holding it ?

A
250 J

B
2500 J

C
0 J

D
625 J

Solution

The work done by a constant force of magnitude $$F$$ on a point that moves a displacement (not distance) $$s$$ in the direction of the force is given by:
$$W = F\times s$$
As the men are just holding the box the value of $$s$$ is $$0$$.
Hence, the work done is $$W=Fs = F\times 0 = 0$$.
Question 8
1 / -0

$$1kWh= $$ _________?

A
$$3600000\ J$$

B
$$10000\ J$$

C
$$4.2\ J$$

D
$$25000\ J$$

Solution

Kilowatt hour is the unit of energy to measure the amount of electricity used in an hour $$1\ kW$$ in $$1\ hr$$.
Hence,
$$1\ kWh = 1 kW \times 1\ hr$$
$$= 10^3 W \times 3600\ s$$
$$= 3600000\ J$$
Question 9
1 / -0

Kilowatt is the unit of electrical _______ but kilowatt-hour is the unit of electrical _______.

A
Power, Energy

B
Power, Electric potential

C
Power, Current

D
Energy, Power

Solution

In SI system, unit of power is Watt (W). Kilowatt is equal to one thousand ($$10^3$$) watts. The kilowatt-hour is a unit of energy and is equal to 1,000 watt-hours. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.
Question 10
1 / -0

An 800 g ball is pulled up a slope as shown in the diagram. Calculate the potential energy it gains.

A
1.96 J

B
1.568 J

C
7.84 J

D
1.225 J

Solution

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Work and Energy Test - 22

Result

Work and Energy Test - 22

Score

-

Rank

-

SHARING IS CARING

Question 1

10 W

15 W

20 W

25 W

Solution

Question 2

$$50\ W$$

$$20\: W$$

$$80\ W$$

$$500\: W$$

Solution

Question 3

$$12\ kWh$$

$$18 \ kWh$$

$$36\ kWh$$

$$6\ kWh$$

Solution

Question 4

$$1360 \:W.$$

$$1.75 \times 10^{17}\:W$$

$$3.5 \times 10^{17}\:W$$

$$7 \times 10^{17}\:W$$

Question 5

$$0\ J$$

$$320\ J$$

$$120\ J$$

$$250\ J$$

Solution

Question 6

Potential energy possessed by stored water is converted into electricity

Kinetic energy possessed by stored water is converted into potential energy

Water is heated to produce electricity

Water is converted into steam to produce electricity

Solution

Question 7

250 J

2500 J

0 J

625 J

Solution

Question 8

$$3600000\ J$$

$$10000\ J$$

$$4.2\ J$$

$$25000\ J$$

Solution

Question 9

Power, Energy

Power, Electric potential

Power, Current

Energy, Power

Solution

Question 10

1.96 J

1.568 J

7.84 J

1.225 J

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.