1) An 18-year-old runner can complete a 10.0 km course with an average speed of 4.52…

1) An 18-year-old runner can complete a 10.0 km course with an
average speed of
4.52
m/s. A 50-year-old runner can cover the same distance with an
average speed of
4.07
m/s. How much later (in seconds) should the younger runner start in
order to finish the the course at the same time as the older
runner?

s

2)
A sprinter explodes out of the starting block with an acceleration
of
+3.8

m/s2,
which she sustains for
1.4
s. Then, her acceleration drops to zero for the rest of the
race.

(a) What is her velocity at
t
=
1.4
s.

m/s

(b) What is her velocity at the end of the race?

m/s

3)
What is the magnitude of the average acceleration of a skier who,
starting from rest, reaches a speed of
8.4
m/s when going down a slope for
6.9
s?

m/s2

How far does the skier travel in this time?

m