Question

A car moves a distance of 200 m. It covers the first half of the distance at speed 40 km/h and second half of the distance at speed v. The average speed is 48 km/h. The value of v is
(1) 56 km/h
(2) 60 km/h
(3) 50 km/h
(4) 58 km/h​

Answer 1

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Answer

First half of distance = 100m

speed = 40km/h or 100/9 m/s

so time taken= 100= 100/9 = 9 second

Given avg speed = 48km/h = 40/3 m/s

Distance= 200m

so total time is 15s

now s has passes covering 100 m. time left = 6s =

Distance left = 100m so speed(v) = 100/6 = 50/3 m/s or 90 km/h

Answer 2

Step-by-step explanation:

Correct option is

D

60 km/h

Given, Distance=200m,Speed=40km/h Average speed =48km/h

48=

40

100

+

v

100

200

⇒

40

1

+

v

1

=

24

1

⇒v=

5−3

120

=

2

120

⇒=60km/h