A car covers the first half of the distance between two stations at a speed of 60 km/h and second half at 80 km/h. Calculate the average speed of the car.
(a)68.57 km/h (b) 78.90 km/h (c) 57.38 km/h (d) none
Answers
Answer:
B)
Explanation:
Letx consider, x= total distance covered by the car,
Time taken to complete the half distance with velocity v=40km/h,
t
1
=
2×40
x
=
80
x
hr. . . . .(1)
The time taken to complete another half distance with velocity u=60km/h
t
2
=
2×60
x
=
120
x
hr
The total time taken, t=t
1
+t
2
t=
80
x
+
120
x
=
48
x
hr
The average speed of the car,
v
avg
=
x/48
x
=48km/hLetx consider, x= total distance covered by the car,
Time taken to complete the half distance with velocity v=40km/h,
t
1
=
2×40
x
=
80
x
hr. . . . .(1)
The time taken to complete another half distance with velocity u=60km/h
t
2
=
2×60
x
=
120
x
hr
The total time taken, t=t
1
+t
2
t=
80
x
+
120
x
=
48
x
hr
The average speed of the car,
v
avg
=
x/48
x
=48km/h