Let the units work for you!

Step 1: Write down the unit you need for your answer on the right side of your paper Step 2: Write down the unit you are starting with on the left side of your paper Step 3: Try putting in equivalent units until they all cancel and give you what you want

Examples of equivalent units 1 min 60 sec 5280 ft mile 12 in ft 60 min hr 1 yard 3 ft 1m 3.3 ft 55 mi 88.5 km 1 mile 1609m 1 yr days

Example In our “constant force” experiment we used a weight to pull cars across the floor. We were surprised to see how much they accelerated (changed speed) Some of the cars reached speeds of 150cm/sec That sounds fast, but what is that in mi/hr?

Step 1- I want an answer in mi/hr, so I will put that on the left Step 2- I have cm/sec so I will put that on the left cm sechr mi Step 3- add equivalencies, one at a time until you can convert the units. I usually leave the numbers out until I determine what units will work

cm sec x = cm hr cm hr x m cm mi m x hr mi= sec 1 hr Remember you are trying to change cm/sec into mi/hr

150 cm sec x = cm hr cm hr x 1 m 100 cm 1mi 1609 m x hr 3.36 mi = 3600 sec 1 hr Remember you are trying to change cm/sec into mi/hr