Question

An electric train of 100 kg mass, when connected to a power source, runs at a velocity of 5 $\frac{m}{s}$. The train runs between station A & B 125m apart and has a capacity of 40 people. If the company is providing electricity to the train at a charging rate of Rs $\frac{100}{watt}$ then what should be the minimum fare of a person on the particular route so that the train doesn’t go in loss? Assuming all energy provided by the power company is used to run the train.

• A. Rs 500
• B. Rs 125
• C. Rs 50
• D. Rs 100

Answer 1

The correct option is B

Rs 125

K.E. of train comes from electrical energy = $\frac{m\ast v^2}{2}$ = 1250J
Power = $\frac{W}{t}$ = $\frac{1250}{timetaken}$
Distance between A & B = 125m & velocity of train = 5 $\frac{m}{s}$​
So, time = $\frac{125}{5}$ = 25 sec
Now, power = $\frac{1250}{25}$ = 50 watt
Rate at which electricity given is Rs$\frac{100}{watt}$
Total cost of journey for 40 people = Rs 5000
So, for 1 person cost will be $\frac{5000}{40}$ = Rs 125