Question

A crane lifts a weight of 10 N up to the height of 5 m in 5 s. What is the power applied by the crane?
1 25 W
2 50 W
3 20 W
4 10 W
please tell the correct one its my online test

Answer 1

Answer:

4) 10 W

Explanation:

Given:

• Weight = 10 N
• Height = 5 m
• Time = 5 s

To find:

• Power applied = ?

Solution:

We know, Power = Work/Time.

We also know, Work = Force × displacement.

So, $\blue{\sf{Power\:=\:\dfrac{F\:\times\:s}{t}}}$

Where, F = force

s = displacement

t = time

We know that weight is also a force. So, in place of force we can put the value of weight.

_______________________________

$\Longrightarrow\:\sf{Power\:=\:\dfrac{10\:\times\:\cancel{5}}{\cancel{5}}}$

$\:$

$\Longrightarrow$ Power = 10 W

$\Longrightarrow\sf{\underline{\underline{\therefore\:Power\:applied\:is\:(4)\:10\:W.}}}$

Answer 2

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

Power applied by crane = 10W

$\red{\mid{\underline{\overline{\textbf{Explanation :-}}}\mid}}$

Work is said to be done when a force is applied on a body and the same body undergoes some displacement. Work is measured in joules. And is the product of force and displacement. It is defined by the expression :

$\bigstar \: \orange{\mid{\underline{\overline{\textbf{w = fs}}}\mid}}$

In this expression :

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

Now, power of machine is the ratio of work done by machine to the time which it took for it. It is defined by the expression :

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

In this expression:

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

Power is Joule per time and is measured in Watts.

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

In this question we have been given that a machine lifts a particular load in a particular time we have to find the power of machine.

Now, important keywords :

• Load Lifted = weight of body = Force applied
• Displacement = 5m
• Time take = 5s

Now, after inputting the known values in expression of work we get :

$\mapsto \: w = 10 \times 5 = 50j$

Therefore work done by machine is 50J.

Now , the power of machine is :

$\mapsto \: p = \frac{w}{t}$

$\mapsto \: p = \frac{50}{5} = 10watt$

Therefore we get power applied by machine to be 10W.

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BY SCIVIBHANSHU

THANK YOU

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