Unit 7 Lesson 2 Velocity
Air/water speed is the
speed of a plane/boat
relative to a person on
board.
Ground speed is the speed
of a plane or boat relative
to a person on the ground
and it includes the effect
of wind or current.
w
r=v+w
v
A plane has a velocity of v (relative
to air when it encounters a wind
having a velocity of w (relative to
the ground).
The resultant velocity r is the
ground speed.
1
Unit 7 Lesson 2 Velocity
?
A plane is flying north with a wind
speed of 400 km/when it encounters
a wind.
What wind direction will give the
greatest ground speed?
What wind direction will give the least
ground speed?
A plane flying north with a wind speed of 350 km/h
encounters a wind from the east blowing at 100 km/h.
Find the resultant velocity.
100
350
vr
𝛳
2
Unit 7 Lesson 2 Velocity
Justin and his friend Callum live directly on opposite sides of a river that
is 0.5 km wide. Justin can swim at a rate of 3 km/h and the river's
current has a speed of 2 km/h. Justin swims directly from his house
across the river to Callum's house.
a) How far downstream will the current push Justin?
Justin and his friend Callum live directly on opposite sides of a river that
is 0.5 km wide. Justin can swim at a rate of 3 km/h and the river's
current has a speed of 2 km/h. Justin swims directly from his house
across the river to Callum's house.
b) How long will it take for Justin to cross the river?
3
Unit 7 Lesson 2 Velocity
Justin and his friend Callum live directly on opposite sides of a river that
is 0.5 km wide. Justin can swim at a rate of 3 km/h and the river's
current has a speed of 2 km/h. Justin swims directly from his house
across the river to Callum's house.
c) If Justin decides that he wants to end up directly at Callum's
house, in what direction should he head? What is the resultant
velocity?
4