Work and Energy Test

Result

Work and Energy Test - 24

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

One megawatt is .................... times that of one kilowatt.

A
$$1000$$

B
$$19600$$

C
$$100000$$

D
$$0.001$$

Solution

One megawatt $$ = 10^6 $$ Watt
One Kilowatt $$ = 10^3$$ Watt
$$\implies \ $$ one megawatt $$ = 1000 $$ kilowatt
Question 2
1 / -0

If force and displacement of the particle (in direction of force) are doubled, Work should be :

A
Doubled

B
Quadrupled

C
Halved

D
Reduced by $$\displaystyle \frac{1}{4} times$$

Solution

Work done is defined as $$W=Fs$$
where $$F$$ is the force applied and $$s$$ is the displacement in the direction of force.

Hence initially work done $$W_1 = Fs$$

Now, When $$F_2=2F$$ and $$s_2=2s$$

Then, work done $$W_2=F_2s_2$$

$$\Rightarrow W_2=(2F)(2s)$$
$$\Rightarrow W_2 = 4W_1$$

Hence, work done is quadrupled.
Question 3
1 / -0

When a force retards the motion of a body, the work done is :

A
Zero

B
Negative

C
Positive

D
Positive or negative depending upon the magnitude of force and displacement

Solution

When the force retards the motion of a body, the work done is negative.
Question 4
1 / -0

The work done in holding $$15\ kg$$ suitcase while waiting for a bus for $$45$$ minutes is :

A
$$675\ J$$

B
$$40500\ J$$

C
$$4500\ J$$

D
$$Zero$$

Solution

Work done = force $$\times$$ displacement in force direction
Work done in holding a suitcase while waiting for a bus i.e. stationary position.
So, displacement will be zero.
Work done = force $$\times$$ zero
Work done = zero
Question 5
1 / -0

Choose the correct option.

A
$$kW=$$ unit of power and $$kWh =$$ unit of energy.

B
$$kW=$$unit of energy and $$kWh =$$ unit of power.

C
$$kW$$ and $$kWh$$ are both of unit of energy.

D
$$kW$$ and $$kWh$$ are both of unit of power.

Solution

Electrical Power is measured in watts ($$W$$), kilo-watts ($$kW$$), mega-watts ($$MW$$), and giga-watts ($$GW$$).

Electrical Energy is measured in kilowatt-hours ($$kWh$$), megawatt-hours, and sometimes (less commonly) in watt-hours or watt-seconds.
Question 6
1 / -0

How much work is done by a force 50 N moving an object through a distance 10 m in the direction of force ?

A
$$5 \ J$$

B
$$500\ J$$

C
$$0.5\ J$$

D
$$0\ J$$

Solution

$$F=50N$$
$$s=10m$$
Work done, $$W=F\times s=50\times 10=500J$$
Question 7
1 / -0

What will be the potential energy of a body of mass 5 kg kept at a height of 10 m ?

A
50 J

B
0.5 J

C
500 J

D
25 J

Solution

Answer is C.

Potential energy is energy stored in an object. This energy has the potential to do work. Gravity gives potential energy to an object. This potential energy is a result of gravity pulling downwards. The gravitational constant, g, is the acceleration of an object due to gravity. This acceleration is about 10 meters per second on earth. The formula for potential energy due to gravity is PE = mgh. As the object gets closer to the ground, its potential energy decreases while its kinetic energy increases.
In this case, a body of mass 5 kg kept at a height of 10 m. So the potential energy is given as 5 * 10 *10 = 500 J.
Hence, the potential energy of a body of mass 5 kg kept at a height of 10 m is 500 J.
Question 8
1 / -0

The work done by a force on a body will be positive if the body -

A
Moves perpendicular to the direction of applied force

B
Does not move

C
Moves along the direction of applied force

D
Moves opposite to the direction of applied force

Solution

Work done is positive when the force is in the direction of displacement.
$$\text{work} = \text{Force} \times \text{displacement in the direction of force}$$
Question 9
1 / -0

An electric toaster draws $$8\ A$$ current in a $$220\ V$$ circuit. It is used for $$2\ hr$$. What is the cost of operating the toaster if the cost of electrical energy is $$Rs.\ 4.5 / kWh$$?

A
$$Rs.\ 9.50$$

B
$$Rs.\ 25.50$$

C
$$Rs.\ 14.84$$

D
$$Rs.\ 15.84$$

Solution

Given,
$$i=8\ A\\E=220\ v\\t=2\ hr$$

Energy dissipated is given by:
$$E = E\ i\ t$$
$$=220 \times 8 \times 2\ Wh$$
$$=3.52\ kWh$$

The cost per kWh is $$Rs.\ 4.50$$
Hence, the cost of running the kettle for two hours is:
$$3.52 \times 4.50 = Rs.\ 15.84$$
Question 10
1 / -0

In our household applications, commercial unit of electricity is used. One unit is equal to:

A
$$1\ kW$$

B
$$1\ kWh$$

C
$$1\ kW/h$$

D
$$1\ Wh$$

Solution

Electrical Energy is measured in kilowatt-hours (kWh). A unit is the primary measurement used by the utility company to determine your bill each month (although demand and power factor are also sometimes used). Unlike power, energy does not change quickly, but instead accumulates gradually.

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Work and Energy Test - 24

Result

Work and Energy Test - 24

Score

-

Rank

-

SHARING IS CARING

Question 1

$$1000$$

$$19600$$

$$100000$$

$$0.001$$

Solution

Question 2

Doubled

Quadrupled

Halved

Reduced by $$\displaystyle \frac{1}{4} times$$

Solution

Question 3

Zero

Negative

Positive

Positive or negative depending upon the magnitude of force and displacement

Solution

Question 4

$$675\ J$$

$$40500\ J$$

$$4500\ J$$

$$Zero$$

Solution

Question 5

$$kW=$$ unit of power and $$kWh =$$ unit of energy.

$$kW=$$unit of energy and $$kWh =$$ unit of power.

$$kW$$ and $$kWh$$ are both of unit of energy.

$$kW$$ and $$kWh$$ are both of unit of power.

Solution

Question 6

$$5 \ J$$

$$500\ J$$

$$0.5\ J$$

$$0\ J$$

Solution

Question 7

50 J

0.5 J

500 J

25 J

Solution

Question 8

Moves perpendicular to the direction of applied force

Does not move

Moves along the direction of applied force

Moves opposite to the direction of applied force

Solution

Question 9

$$Rs.\ 9.50$$

$$Rs.\ 25.50$$

$$Rs.\ 14.84$$

$$Rs.\ 15.84$$

Solution

Question 10

$$1\ kW$$

$$1\ kWh$$

$$1\ kW/h$$

$$1\ Wh$$

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.