Question

A motor lifts a load of 3000
N through a vertical distance of 10 m in 20 s.
What is the average power during this operation?
1 300 W
2 1500 W
3 30,000 W
4 15,000 W
please tell the correct on its my online test

Answer 1

$\red{\mid{\underline{\overline{\textbf{Answer}}}\mid}}$

Average power = 1500W (B)

$\red{\mid{\underline{\overline{\textbf{explanation}}}\mid}}$

Work is said to be done when a force is applied on a body and the body undergoes displacement.

Work is measured in Joules. Work is defined by the expression :

$\bigstar \: \orange{\mid{\underline{\overline{\textbf{w = f×s}}}\mid}}$

In this equation :

• w = work done
• f = Force applied
• s = displacement of body

Power of a machine is defined as the work it does in a period of time. It is defined by the expression :

$\bigstar \: \orange{\mid{\underline{\overline{\textbf{p = w/t}}}\mid}}$

In this equation :

• p = power of machine
• w = work done
• t = time period

$\blue{\mid{\underline{\overline{\textbf{Coming to question :-}}}\mid}}$

In this question we have been given the time in which a machine lifts a particular load, power of machine is not known we have to calculate it.

Since machine lifts load of 3000N thus the force applied will also be 3000N

Now we can say :

• Force applied by machine = 3000N
• Displacement of load = 10m
• In time = 20s

Now work done by the machine will be :

$\mapsto \: w = 3000 \times 10 = 30000j$

Now the power of machine will be :

$\mapsto \: p = \frac{30000}{20}$

$\mapsto \: p = \cancel \frac{30000}{20} = 1500watt$

Therefore power of given machine is 1500W.

Which is Option B.

______________________________________

BY SCIVIBHANSHU

THANK YOU

STAY CURIOUS

Answer 2

Given :-

Force of the load lifted = 3000 N

Displacement covered by the motor = 10 m

Time taken by the motor = 20 sec

To Find :-

The average power during this operation.

Analysis :-

Here we are given with the force, displacement and the time taken by the motor.

Firstly find the work done by substituting the values such that work done is equal to force multiplied by displacement.

Then using the formula of power, find the power of the operation accordingly.

Solution :-

We know that,

• w = Work done
• f = Force
• s = Displacement
• p = Power
• t = Time

Using the formula,

$\underline{\boxed{\sf Work \ done=Force \times Displacement}}$

Given that,

Force (f) = 3000 N

Displacement (s) = 10 m

Substituting their values,

⇒ w = fs

⇒ w = 3000 × 10

⇒ w = 30000 J

Using the formula,

$\underline{\boxed{\sf Power=\dfrac{Work \ done}{Time \ taken } }}$

Given that,

Work done (w) = 30000 J

Time (t) = 20 sec

Substituting their values,

⇒ p = w/t

⇒ p = 30000/20

⇒ p = 1500 W

Therefore, the average power during this operation is (2) 1500 W.