Question

find the time taken by a car running at 25m/s to cover a distance of 360km in hours

Answer 1

Speed = 25m/s

Distance = 360km

First, we need to change the speed to km/h.

25m/s = 25m/1s

= (25 ÷ 1000)km/(1 ÷ 3600) hours

= 0.025km/0.000278 hours

Find 0.025km/0.000278 hours in km per hour (km/hour).

0.025km ÷ 0.000278 hours = 90km

25m/s = 90km/h

Calculate the time taken using the formula Time = Distance ÷ Speed.

360km ÷ 90km/h = 4 hours

Hence, the time taken by the car is 4 hours.

Answer 2

Answer:

Let the each half of the running time be t.

During first half time, speed of car is 80 km/h

Distance covered d

1

=80t km

During second half time, speed of car is 40 km/h

Distance covered d

2

=40t km

Total distance covered d=d

1

+d

2

=80t+40t=120t

Total time taken T=2t

Average speed v

avg

=

T

d

=

2t

120t

=60 km/hr

Option C is correct.