The cost of fuel of an engine varies as the square of its velocity and the cost of fuel is ₹ 48 per hour when the velocity is 16 km per hour. If other expenses be ₹ 300 per hour, then show that the most economical velocity for a journey of a given distance is 40 km per hour.

Assuming the petrol burnt per hours in driving a motor boat varies as the cube of its velocity, show that the most economical speed when going against a current of c km per hour is (3c )/(2) km per hour.

Calculate the wavelength of 1000 kg rocket moving with a velocity of 300 km per hour.

The time required by a motor car to travel a cartain distance is 3 hours less if its velocity be increased by 9 kilometres per hour. Again ,if the velocity be decreased by 6 kilometres per hour , then the time required by the car to travel the same distance is 3 hours more. Find the velocity of the car and the certain distance.

A man travels a distance in 3 hours with a uniform velocity . If the distance be 2 km more and his velocity be 2 km less per hour then he will take time 1 hour more to travel the new distance . Find the uniform velocity of the man.

The radius of the wheel of a train is 0.35 m. If the wheel rounds 450 times in one minute, then find the velocity of the train per hour.

The fuel charges for running a train are proportional to the square of the speed generated in km/h, and the cost is Rs. 48 at 16 km/h. If the fixed charges amount to Rs. 300/h, the most economical speed is (a) 60 km/h (b) 40 km/h 48 km/h (d) 36 km/h

A man has to spend Rs.16 per km on petrol if he rides his motor-car at 30 km per hour and the cost on petrol rises to Rs.20 per km if he rides his car at 45 km per hour. He has Rs.200 to spend on petrol and desires to travel maximum distance within 2 hours. Formulate the given data in the form of inequations and show graphically the region representing the solution of the inequations.

Find the distance covered by a car in 2(2/5) hours at a speed of 46(2/3) km per hour.