WEBVTT

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Do you have a friend or a sibling

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that's always competing with you

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to see who's the fastest?

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Our alien friends Bleebop and Mark

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are having the same debate

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with their custom-built rockets,

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and they've asked us

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to be the judge of a space race to their moon.

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The only problem is that they are starting

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from different asteroids.

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Bleebop is on an asteroid 240 miles from the moon,

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and Mark is on one 150 miles away.

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Don't worry, it's not rocket science.

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Solving this equation is as simple as DIRT.

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We can decide who the winner is

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using the D=RT formula, or DIRT.

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This stands for distance equals rate times time.

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In the case of Bleebop and Mark,

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we will only know the distance they traveled

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and the time it took for them

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to get to the finish line.

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It'll be up to us to find the rate

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and who is faster.

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Let's turn to the race now

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and see what information we get.

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Three,

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two,

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one,

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blast off!

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Bleebop and Mark's rockets go zipping

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across the galaxy towards their moon,

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dodging clunky meteorites

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and loopy space buggies.

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After a few close calls with a wandering satellite,

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Mark arrives first in two hours,

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and Bleebop gets there one hour later.

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Looks like Mark has the faster rocket,

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but let's check out the results with our DIRT equation.

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Begin by setting up a chart.

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Make four columns and three rows.

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Use DIRT to remember what to fill in.

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Each rocket will have information

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for distance, rate, and time.

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Mark's rocket went 150 miles,

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we don't know the rate,

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and he got there in 2 hours.

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Bleebop's rocket went 240 miles,

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we don't know the rate,

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and the time is 1 hour after Mark,

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or 3 hours.

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Because we don't know Mark or Bleebop's rate,

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that number is going to be a variable

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in each equation,

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which we'll represent with x.

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We'll solve the equation

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for the variable to find its value.

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Mark finished first,

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so start with his rocket.

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Remembering DIRT, write down D=RT.

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150 miles equals x times 2 hours.

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Divide both sides by 2 hours.

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This will leave x isolated

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on the right side of the equation.

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150 miles divided by 2 hours

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is 75 miles over 1 hour.

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Mark's rate is 75 miles per hour.

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That's what mph means.

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It's the amount of miles over one hour.

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Still think Mark is faster?

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Let's set up the same equation for Bleebop and see.

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D=RT

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240 miles equals x times 3 hours.

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Divide both sides by 3 hours.

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This will leave x isolated

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on the right side of the equation.

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240 miles divided by 3 hours

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is 80 miles over 1 hour.

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Bleebop's rate is 80 miles per hour.

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Wow, even though Bleebop got there one hour later,

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it turns out he had the faster rocket.

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Mark seems pretty upset,

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but with aliens, you can never really tell.

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Thanks to DIRT, you now know how to calculate

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distance,

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rate,

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and time.

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In what other situations

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can you use the distance formula?

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You don't even need to be watching a space race.

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As long as you know two pieces of information

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for the formula D=RT,

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you can calculate any moving vehicle or object.

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Now, the next time you're in a car,

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you can let your friends know

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exactly when you'll be arriving,

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how fast you're going,

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or the distance you'll travel.

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It's as simple as DIRT.