Question

21. A car moving over a straight path,
covers a distance d with constant speed
of 40 km/hr and then the same distance
with speed 60 km/hr. The average speed
of car is ....
(A) 50 km/hr
(B) 48 km/hr
(C) 52 km/hr
(D) None of the given options
U
19​

Answer 1

Answer:

Explanation:

Given :

▪ A car covers first half of total distance with speed 40kmph and second half of total distance with speed 60kmph.

To Find :

▪ Average speed of the car.

Concept :

✏ If body covers first half of total distance with speed v1 and second half of total distance with speed v2, then average speed of the body is given by

☞ (v)av = 2v1v2/v1+v2

✏ Average speed is defined as the ratio of total distance travelled to the total time taken.

✏ It is a scalar quantity.

Calculation :

→ (v)av = 2v1v2/v1+v2

→ (v)av = 2(40)(60)/(40+60)

→ (v)av = 4800/100

→ (v)av = 48kmph