Question

A car travelled the first third of a distance at a speed of 10Kmph, the second third at a speed of 20Kmph and the last third at a speed of 60Kmph. Determine the average speed of the car over the entire distance.​

Answer 1

Answer:

Let the total distance traveled be s.

Hence the time taken for first third of the distance= t

1

=

v

1

s/3

Similarly, the time taken for second third of the distance= t

2

=

v

2

s/3

and the time taken for last third of the distance= t

3

=

v

3

s/3

Hence the mean speed over the distance=

t

1

+t

2

+t

3

s

=

v

1

1

+

v

2

1

+

v

3

1

3

=18km/h