Question

 An engine pumps out 40k.g of water per second. If water comes out with a velocity of 3 m/s,  then what is the power of engine?

Answer 1

Here ,
M= 40 kg
v= 3m/s
t=1s
applying the formula of power 
i.e.
P=$\frac{work done}{time}$
here work done is equal to the KE of the body i.e.
KE=0.5*m*v²
     =0.5*40*9
     =180 J
substituting the value of work done and time taken we get
P=$\frac{180}{1}$
P=180J/s or 180 W

Answer 2

Answer:

The power of the engine is 180w.

Explanation:

• Kinetic energy exists directly proportionate to the mass of the object and to the square of its velocity:
• $K.E _{.}=\frac{1}{2} m v^{2}$
• If the mass has units of kilograms and the velocity of meters per second, the kinetic energy retains units of kilograms-meters squared per second squared.

From the question, it is given that,

$\mathrm{m}=40 \mathrm{~kg}$

$\mathrm{v}=3 \mathrm{~m} / \mathrm{s}$

$\mathrm{t}=1 \mathrm{~s}$

Applying the equation,

$K.E _{.}=\frac{1}{2} m v^{2}$

K.E.$=\frac{1}{2} \times 40 \times 3^{2}$

We get,

$\text { K.E. }=180 \mathrm{~J}$

Therefore,

Power $=\frac{E}{t}=\frac{180}{1}=180 \mathrm{w}$

Hence the power of engine is 180w.

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