Question

Assuming that be petrol burnt in a motor boat varies as the cube of its velocity, the most economical speed when going against a current of ckm/hr is 

Solution

Correct option is

(3c/2 km/hr)

Economy for speed = average speed per litre of petrol burnt.

Let relative speed of the boat = v km/hr

  

and absolute speed of the boat = (v – c) km/hr

  

  

   

  

 

SIMILAR QUESTIONS

Q1

Total number of critical points of (x) = maximum (sin x, cos x) ∀ x Ïµ (–2π, 2π) equal to   

 

Q2
Q3

As an example consider the function (x) = – (–x)5/5, –1 ≤ x ≤ 0. Then at (0, 0) (x) has 

Q5

 then f’(0) is equal to 

Q6

 

  

Local minimum at x = 2, then

 

Q9

 

 a minimum at x= 1 is the value of a is