Question

A machine does 4 joule of work in 2 second. Calculate its power?

Answer 1

${\bf \underline{ \underline{Given}}}$

• Work done = 4 joules

• Time taken = 2 Seconds

$\bf{ \underline{ \underline{To \: be \: calculated}}}$

Calculate the power?

$\bf{ \underline{ \underline{Formula \: used}}}$

$\boxed{Power = \frac{Work \: done}{Time \: taken} }$

$\bf{\underline{ \underline{Solution}}}$

We know, Work done and time taken. So,we can calculate the power by using the formula;

Power = Work done/Time taken

★ Substituting the values in the above formula,we get:

Power = 4 joules / 2 seconds

= 2 J/s

We know, 1 Watt = 1 joules / 1 seconds

= 2 W

Thus,the power of machine is 2 watts .

Additional information:

Power: Rate of work done is called Power.

• S.I unit of Power is watt.

• Scalar quantity [ It has only magnitudes ]

• Commercial unit of power is Horse power.

Answer 2

Given that ,

Work done (w) = 4 j

Time (t) = 2 sec

As we know that ,

The rate of work done is called power

$\sf \large \underline{ \fbox{Power = \frac{w}{t} }}$

The SI unit of power is watt or j/s

Thus ,

$\sf \Rightarrow Power = \frac{4}{2} \\ \\ \sf \Rightarrow Power = 2 \: watt$

$\therefore \underline{ \sf \bold{ {The \: power \: is \: 2 \: watt \: }}}$