Placeholder Image

Subtitles section Play video

  • 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.

Do you have a friend or a sibling

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B1 US TED-Ed rocket equation distance hour space race

【TED-Ed】A trip through space to calculate distance - Heather Tunnell

  • 5712 414
    Kevin Tan posted on 2014/08/19
Video vocabulary