Question

on a 100km road. a car travel the first 50km at uniform speed of 30km/h.How fast the car travel 50km . also as have an average speed of 45km/h for the entire journey
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Answer 1

Answer:

90 km/hr fast must the car travel for the next 50 km

Explanation:

Given that,

Total distance = 100 km

First distanced_{1} = 50\ kmd 1

=50 km

Speedv_{1} = 30\ km/h^{-1}v 1

=30 km/h −1

The car travels 50 km with speed 30 km/hr.

The time taken is

t=\dfrac{d}{v}t= vd

t_{1}=\dfrac{50}{30}t 1

= 50

30

t_{1}= 1.67\ hrt 1

=1.67 hr

Let us consider, the car travels next 50 km with speed v₂ km/hr.

The time taken is

t_{2}= \dfrac{50}{v_{2}}t 2

= v 250

The average speed v_{avg}=\dfrac{D}{T}v

avg

= TD

Here, D = total distance

T= total time

The average speed is

45=\dfrac{100}{\dfrac{5}{3}+\dfrac{50}{v_{2}}}45=35+ v 2

50

100

v_{2}=90\ km/hr v 2

=90 km/hr

Hence, 90 km/hr fast must the car travel for the next 50 km.

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