Question

A train is travelling on level track at a speed of 72km/h. it is pulled by an engine which exerts a force of 12000n. calculate the power of engine in kilowatt

Answer 1

Given:

$\dag\: \sf\ Speed = 72km/h$

$\dag\: \sf\ Force = 12000N$

To Find:

Power of engine in kilowatt.

Solution:

$\sf\ Here\: we\: have\: to\: find \: Power \:of\: engine.$

Conversion:

$\sf\ 1 km = 1000m$

$\sf\ 1 hr = 3600sec$

$\sf\large\ = 72\times \frac{5}{18}$

$\dashrightarrow\: \underline{\boxed{\bf{\orange{ 20m/s}}}}$

Calculation:

$\underline{\boxed{\bf{\purple{Formula:- P = FV}}}}$

$\dashrightarrow\: \sf\ Force×Velocity$

$\dashrightarrow\: \sf\ 12\times10^3N\times 20m/s$

$\dashrightarrow\: \sf\ 24\times10^4W$

$\dashrightarrow\: \underline{\boxed{\bf{\red{240kw}}}}$

$\rule{180}3$

$\large\underline\bold{Additional\: Information}$

• Power is the rate of doing work or the rate of transfer of energy.
• If W is the amount of work done in time t, then power is given by the expression,
• It is expressed in watt (W).
• Formula :- P = FV

$\rule{180}3$

Answer 2

The correct answer is 240 kw.

Given: Speed = 72 km/hr and Force = 12000 N.

To Find: Power of Engine.

Solution:

Firstly, convert km/hr in m/sec.

72 × $\frac{5}{18}$ = 20 m/sec.

As we know,

P = FV

= 12000 × 20

= 240 kw.

Hence, the power of engine is 240 kw.

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