# Internal 3 Credits DO NOW: Turn to page 177 and do problem 9.

## Presentation on theme: "Internal 3 Credits DO NOW: Turn to page 177 and do problem 9."— Presentation transcript:

Internal 3 Credits DO NOW: Turn to page 177 and do problem 9.

 What is it?  A rate compares 2 quantities measured in different units.  Example of rates?  45 wpm, 80 km/h,

 The graph on the right shows distance travelled over time.  Let’s calculate the gradient.  Gradient = Rise / Run  160 km / 2 h =  80 km / h 2 h 160 km The gradient of the graph is the rate!

This shows B is growing at a faster rate. The gradient for the line in B is steeper than for the line in A. How do we know that it is steeper? 60 000 198519952005 40 000 20 000 Population 1975 B 60 000 198519952005 40 000 20 000 Population 1975 A The graph shows the growth in population for two towns. The gradient for the line in B is steeper than for the line in A. Which town is growing at a faster rate?

Town A grows from to 10 000 in 1975 50 000 in 2005 The population increase per year is = 667 people per year This is an increase of 20 000 in 30 years. The graph shows the growth in population for 2 towns.What are the rates? Town B grows from to 40 000 in 2005 The population increase per year is = 1000 people per year This is an increase of 30 000 in 30 years. 30 000 in 1975 60 000 198519952005 40 000 20 000 Population 1975 B 60 000 198519952005 40 000 20 000 Population 1975 A

 Turn to page 182 and do the following problems:  1, 3, 9, 10, 13, 16, 21

 Speed is the rate at which distances travelled changes over time. Usually called Velocity.  Units:  Distance – km or m  Time – h or s  Velocity – km/h or m/s

 For this level, we only work with average speed.  For example: Car travels 360 km over 4 hours, we say that the average speed is  360/4 = 90 km/h (even though the car would have travelled faster over some sections)

 Distance = Velocity * Time  Velocity (or speed) = distance / time  Time = Distance / Velocity (or speed) Dist. Vel.Time

Gamma Mathematics Workbook © Pearson Education New Zealand 2007 A cyclist travels at a steady speed of 24 km/h for 40 minutes. How far does the cyclist travel? hoursminutes Units are not consistent Make sure the units for time are consistent. 40 minutes = ? hours distance = = 16 km Distance = speed  time

Gamma Mathematics Workbook © Pearson Education New Zealand 2007 How many minutes does it take to run 1500 m at an average speed of 10 km/h? metres kilometres Units are not consistent Make sure the units for distance are consistent. 1500 m = ? km time = = 9 minutes speed distance time  Multiply by 60 to get minutes.

 Turn to page 185 and complete the following problems:  1, 3, 4, 5, 6, 11, 12, 16

Download ppt "Internal 3 Credits DO NOW: Turn to page 177 and do problem 9."

Similar presentations