Unit Conversions

Objectives Learn how to convert units by using know conversion

ratios. Apply these conversions to answer questions.

Converting Units Why do we convert units?

We are needy people and try to always get what we want.

Also physics doesn’t work if you use the wrong units

The basics Converting prefixes Example

15kg to g

1302mL to L

15,000g

1.302L

The next level Converting between systems They (me) will give you the ratio before asking you to

do this Example

Convert 3 miles to meters (1 mile is 1609.34meters)

Practice Convert 2.5 miles to meters (1 mile is 1609.34meters)

Convert 6 miles to km (1 mile is 1609.34meters)

With a partner Convert

3 weeks into hours

3,600 seconds to hours

1,200 yards to feet

The next next level Convert 60 mph to m/s (1 mile is 1609.34 meters)

400 feet per second to m/s (1 meter is 3.28 feet)

30mph to km/h ( 1 mile is 1609.34 meters)

Partner Practice Convert the following speeds. Show all units as well as

cancellations. a) 25 km/h to m/s b) 150 km/h to m/s c) 2.0 m/s to km/h d) 50 m/s to km/h

Answers a) 6.9 m/s b) 41.7 m/s c) 7.2 km/h d) 180 km/h

The next next next level a) The maximum speed reached by a standing

skateboarder is about 14.7 m/s. Would the skateboarder get a ticket in a 30 km/h speed zone?

b) A snail crawls 100 times slower than a normal human walk (3 km/h). How many times slower than the skateboarder is the snail?

Answers a) yes, speed of 52.9 km/h b) 1763 times slower

Checkpoint Can you apply your knowledge of unit conversions to

solve more complex questions?