6. Humans reach terminal velocity of 180-230 kmh-1 after
10-12 seconds of free-fall.
In sky-diving, experienced jumpers can reach speeds
of over 200 kmh-1 by falling head-first in a straight-
bodied position (which limits air resistance).
The fastest bird is
the peregrine
falcon which can
reach speeds of
324 kmh-1 when
diving to catch
and kill its prey.
Its amazing
swooping speed
makes it the
fastest creature
on earth.
The fastest fish is the sailfish which has been clocked
leaping out of the water at speeds of 110 kmh-1.
The fastest land
animal is the
cheetah which
can maintain
speeds of 100
kmh-1 for up to
550m.
What do you think is the fastest:
• land animal?
• fish?
• bird?
Estimate the maximum speed that each is
able to reach.
In what popular adventure activity do
humans reach their terminal velocity?
What speed can they reach?
17. In 10 seconds, a car speeds
up uniformly from a speed of
12 ms-1 to 27 ms-1.
Calculate its acceleration.
Working:
Therefore:
a =
▲v
▲t
▲v = 27 - 12
= 15 ms-1
▲t = 10 seconds
a =
15
10
= 1.5 ms-2