A trip through space to calculate distance - Heather Tunnell

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Imagine two aliens racing across outer space to their moon. Who can we deem the fastest alien? With DIRT -- or the equation Distance = Rate x Time -- we can calculate their rates, using the distance they traveled and the time they took. Heather Tunnell explains how to use this helpful equation to determine which of our alien friends is truly faster.

Lesson by Heather Tunnell, animation by Karrot Animation.

Do you have a friend or a sibling

that's always competing with you

to see who's the fastest?

Our alien friends Bleebop and Mark

are having the same debate

with their custom-built rockets,

and they've asked us

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

The only problem is that they are starting

from different asteroids.

Bleebop is on an asteroid 240 miles from the moon,

and Mark is on one 150 miles away.

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

Solving this equation is as simple as DIRT.

We can decide who the winner is

using the D=RT formula, or DIRT.

This stands for distance equals rate times time.

In the case of Bleebop and Mark,

we will only know the distance they traveled

and the time it took for them

to get to the finish line.

It'll be up to us to find the rate

and who is faster.

Let's turn to the race now

and see what information we get.

Three,

two,

one,

blast off!

Bleebop and Mark's rockets go zipping

across the galaxy towards their moon,

dodging clunky meteorites

and loopy space buggies.

After a few close calls with a wandering satellite,

Mark arrives first in two hours,

and Bleebop gets there one hour later.

Looks like Mark has the faster rocket,

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

Begin by setting up a chart.

Make four columns and three rows.

Use DIRT to remember what to fill in.

Each rocket will have information

for distance, rate, and time.

Mark's rocket went 150 miles,

we don't know the rate,

and he got there in 2 hours.

Bleebop's rocket went 240 miles,

we don't know the rate,

and the time is 1 hour after Mark,

or 3 hours.

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

that number is going to be a variable

in each equation,

which we'll represent with x.

We'll solve the equation

for the variable to find its value.

Mark finished first,

so start with his rocket.

Remembering DIRT, write down D=RT.

150 miles equals x times 2 hours.

Divide both sides by 2 hours.

This will leave x isolated

on the right side of the equation.

150 miles divided by 2 hours

is 75 miles over 1 hour.

Mark's rate is 75 miles per hour.

That's what mph means.

It's the amount of miles over one hour.

Still think Mark is faster?

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

D=RT

240 miles equals x times 3 hours.

Divide both sides by 3 hours.

This will leave x isolated

on the right side of the equation.

240 miles divided by 3 hours

is 80 miles over 1 hour.

Bleebop's rate is 80 miles per hour.

Wow, even though Bleebop got there one hour later,

it turns out he had the faster rocket.

Mark seems pretty upset,

but with aliens, you can never really tell.

Thanks to DIRT, you now know how to calculate

distance,

rate,

and time.

In what other situations

can you use the distance formula?

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

As long as you know two pieces of information

for the formula D=RT,

you can calculate any moving vehicle or object.

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

you can let your friends know

exactly when you'll be arriving,

how fast you're going,

or the distance you'll travel.

It's as simple as DIRT.