This document discusses velocity and how to calculate it. It provides examples of: 1) Converting between different units of velocity like km/day, km/hr, km/min, km/s, and km/ms. 2) Calculating the resultant velocity when vectors are added, such as an airplane's velocity in tailwinds, headwinds, and crosswinds. 3) Solving word problems involving velocity and river currents, like calculating how fast a boat travels when crossing a river with a running current.

1. Starter -Match the
velocities
30 km day-1
30 km hour-1
30 km min-1
30 km s-1
300 km ms-1
Make a little
table

2. Velocity vectors
Mapping space and time lesson 4

3. LI…
 Know that velocity is a vector
 Use velocity = displacement/time (v =s/t)
 Resolve velocity vectors

4. Scalar or vector
 Speed is scalar
speed = distance
time
v = s / t
Measured in metres
per second ms-1
 Velocity is a vector
velocity = displacement
time
v = s / t
Measured in metres
per second ms-1

5. Velocity and speed of
earth around the sun
 Speed is large and constant
 Velocity changes all the
time
 Average velocity over one
year is zero
sun
dec
jun
mar
jul
sep
y
x

6. Adding vectors – tail wind
 A plane can fly at 120 ms-1 in calm conditions, if it
has a tail wind of 20 ms-1, how fast will it fly?
 The resultant velocity is the sum of the two. You
add them.
 To add vectors you put them tip to tail.
120 ms-1
140 ms-1
20 ms-1

7. Adding vectors – Head
wind
 A plane can fly at 120 ms-1 in calm conditions, if it has a
head wind of 20 ms-1, how fast will it fly?
 The resultant velocity is the sum of the two. You add
them.
 To add vectors you put them tip to tail.
120 ms-1
100 ms-1
20 ms-1

8. Adding vectors – Cross wind
 A plane can fly at 120 ms-1 in calm conditions, if it has a
cross wind of 20 ms-1, how fast will it fly?
 The resultant velocity is the sum of the two. You add
them.
 To add vectors you put them tip to tail.
120 ms-1
122 ms-1
20 ms-1
20
120

9. River crossing
 A motor boat can travel at 5 ms-1 in calm
conditions.
 The boat makes a crossing from the
south to north shore. The skipper
maintains a northward heading.
 The river runs west to east at 2 ms-1.
 What is the velocity of the boat as it
crosses? If the river is 50m where does
he land?
North shore
South Shore
2 ms-1

10. River crossing 2
 A motor boat can travel at 5 ms-1 in calm
conditions.
 The river runs west to east at 2 ms-1.
 The boat makes a crossing from the
south to north shore. The skipper
navigates along the route shown.
 What is the velocity of the boat as it
crosses? What direction does he need
to steer?
 How long does he take?
North shore
South Shore
2 ms-1