Work and Energy Test

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Work and Energy Test - 35

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Weekly Quiz Competition

Question 1
1 / -0

Directions For Questions

A porter is carrying a load of 50 kg.

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(i) What is the work done by the porter when he climbs up a height of 10 m $$\displaystyle (g\quad = 10\ {ms} ^{-2})$$?

A
$$5kJ^2$$

B
$$50kJ$$

C
$$100kJ^2$$

D
$$5kJ$$

Solution

The work done by the potter is defined as the product of the force and the displacement.

Work done = force $$\times$$ displacement
= $$m \times g \times 10$$ ( Since force = mass $$\times$$ gravity)

= $$50 \times 10 \times 10$$
= $$5KJ$$
Question 2
1 / -0

A force of $$5\ N$$ causes a displacement of $$10\ m$$ in its direction. Calculate the work done by the force.

A
$$15\ J$$

B
$$25\ J$$

C
$$50\ J$$

D
$$200\ J$$

Solution

Given,
Force applied, $$F=5\ N$$
Displacement, $$d=10\ m$$

We know,
Work done, $$W=F\times d$$
$$W=5\times 10$$
$$W=50\ J$$
Question 3
1 / -0

What is the work done by a force of 2 N in displacing a body by 2 m in the direction of the force?

A
$$4J^2$$

B
$$6J$$

C
$$4J$$

D
$$48J$$

Solution

Work done is given by
$$Work \quad done=Force \times Displacement$$
$$Force=2N$$ $$Displacement=2m$$
So $$Work\quad done $$= $$2 \times 2$$ =$$4J$$
Question 4
1 / -0

An electric heater has a rating of 2 kW, 220 V. The cost of running the heater for 10 hours at the rate of Rs 350 per unit is Rs ____

A
216

B
165

C
209

D
105

Solution

Power is energy consumed per unit time.

Here, energy consumed$$=P=2kW=2000W$$ and time$$=t=10hr=36000s$$

$$P=\dfrac{E}{t}$$

$$\implies E=Pt=2kW\times 10h=20kWh=20units$$

Since $$1unit=1kWh$$

Cost$$=20\times 350=Rs 7000$$
Question 5
1 / -0

What is the work done by gravity on a load of $$50 \ kg$$ carried by porter while walking along the platform?

A
$$0 J$$

B
$$10 J$$

C
$$50 J$$

D
$$500 J$$

Solution

Force of gravity and displacement of load carried by the porter are perpendicular to each other.
Hence, work done by gravity on the load is zero.
Question 6
1 / -0

The energy directly related to the speed of a moving body and its mass is:

A
kinetic

B
potential

C
solar

D
electric

Solution
Question 7
1 / -0

A heavy object has ....... gravitational potential energy than a lighter one.

A
less

B
more

C
same

D
none of these

Solution

Gravitational potential energy is given by
$$PE=mgh$$
where $$m$$ is mass so heavy object means more mass and more mass means more potential energy.
Question 8
1 / -0

The electricity tariff in a town is $$Rs.3.00$$ per unit. Calculate the cost of running an $$80 W$$ fan for $$10 h$$ a day for the month of June.

A
$$Rs. 12.00.$$

B
$$Rs. 52.00.$$

C
$$Rs. 72.00.$$

D
$$Rs. 92.00.$$

Solution

Total time for which the fan is used $$= (10 hours) \times (30 days) = 300$$ hours.
Energy consumed $$= (80 W) \times (300$$ hours$$)$$
$$= 24,000 Wh = 24 kWh.$$
But $$1 kWh =1$$ unit.
Therefore, $$24 kWh = 24$$ units
The cost of this power $$= 24$$ units $$\times Rs. 3= Rs. 72.00.$$
Question 9
1 / -0

Which one of the following types of energy is possessed by a body when placed at a certain height?

A
Kinetic energy

B
Potential energy

C
Heat energy

D
Sound energy

E
None of these

Solution

When a body is placed at a certain height, the body possesses potential energy.

$$P.E. = mgH$$
$$m$$; the mass of the object
$$g$$; acceleration due to gravity
$$H$$; height gained by object
Question 10
1 / -0

Calculate the work done when a 2N force moves a body through a distance of 10 m.

A
10 J

B
2 J

C
5 J

D
20 J

Solution

Work done = Force applied x Distance moved
$$W=F \times s$$
$$ W = 2 \times 10 = 20\ J $$

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Re-Attempt Weekly Quiz Competition

Work and Energy Test - 35

Result

Work and Energy Test - 35

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SHARING IS CARING

Question 1

$$5kJ^2$$

$$50kJ$$

$$100kJ^2$$

$$5kJ$$

Solution

Question 2

$$15\ J$$

$$25\ J$$

$$50\ J$$

$$200\ J$$

Solution

Question 3

$$4J^2$$

$$6J$$

$$4J$$

$$48J$$

Solution

Question 4

216

165

209

105

Solution

Question 5

$$0 J$$

$$10 J$$

$$50 J$$

$$500 J$$

Solution

Question 6

kinetic

potential

solar

electric

Solution

Question 7

less

more

same

none of these

Solution

Question 8

$$Rs. 12.00.$$

$$Rs. 52.00.$$

$$Rs. 72.00.$$

$$Rs. 92.00.$$

Solution

Question 9

Kinetic energy

Potential energy

Heat energy

Sound energy

None of these

Solution

Question 10

10 J

2 J

5 J

20 J

Solution

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