Question

A train weighing 10^7 N is running on a level track with uniform speed of 36 km/h. the frictional force is
0.5 kgf per quintal. What is the power of the engine - (g = 10 m/s2)
(1) 0.5 kw
(2) 5 kw
(3) 50 kw
(4) 500 kw

(Ans is 500kw)
please briefly explain...
❌❌(irrelevants will get report )​

Answer 1

Weight of the train = 10⁷ N

Speed of the train = 36 km/h = 36 × $\dfrac{5}{18}$ = 10 m/s

As, 1 kgf = 10 N

So, 0.5 kgf = 0.5 × 10 N = 5 N

Now, $\sf f_{net}$ = $\dfrac{5}{1000}$ × 10⁷ N = 5 × 10⁴ N

Power = $\sf f_{net}$ × speed

P = 5 × 10⁴ N × 10 m/s

P = 5 × 10⁵ N-m/s

P = 500000 W

P = 500kW

$\bold{Hope\;it \; helps\;!}$

Answer 2

Answer:

Weight of the train = 10⁷ N

Speed of the train = 36 km/h = 36 × \dfrac{5}{18}

18

5

= 10 m/s

As, 1 kgf = 10 N

So, 0.5 kgf = 0.5 × 10 N = 5 N

Now, \sf f_{net}f

net

= \dfrac{5}{1000}

1000

5

× 10⁷ N = 5 × 10⁴ N

Power = \sf f_{net}f

net

× speed

P = 5 × 10⁴ N × 10 m/s

P = 5 × 10⁵ N-m/s

P = 500000 W

P = 500kW

\bold{Hope\;it \; helps\;!}Hopeithelps!