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Why a Falling Raindrop Stops Speeding Up

8th grade nonfiction passage about air resistance and terminal speed: 255 words, six questions, an answer key and vocabulary.

8th grade nonfiction air resistance and terminal speed 255 words

Why a Falling Raindrop Stops Speeding Up

A raindrop can fall from a cloud that sits well above the tops of the tallest buildings. If nothing slowed it down, gravity would keep making it go faster and faster, and a drop arriving at the ground would hit like a tiny bullet, but in real life, raindrops tap against umbrellas gently. The reason is air, which pushes back against anything that moves through it.

When the drop first begins to fall, it moves slowly, and the air barely notices it, but gravity pulls it downward, and the drop speeds up. As its speed grows, the air pushes back harder, because the drop has to shove more air out of its way every second. This opposing push is called air resistance, or drag, and it points upward, against the direction of the motion.

Soon the drop reaches a speed where the upward push of the air equals the downward pull of gravity, and because the forces are balanced, the drop stops gaining speed and falls at a steady rate. This steady speed is called terminal velocity.

Terminal velocity is different for different objects. A larger raindrop falls faster than a small drizzle drop, which is why heavy rain falls faster than mist. A skydiver can change it too. Spreading out the arms and legs gives the air more to push against, and a parachute gives it far more, which brings the steady speed down to a safe, gentle landing. Air resistance is not just an obstacle. It is a kind of built-in brake.

Questions

  1. What would happen to a raindrop if nothing slowed it down? in the text

  2. In which direction does air resistance push on a falling drop? in the text

  3. Why does the air push back harder as the drop speeds up? think about it

  4. What is true about the forces when a drop reaches terminal velocity? in the text

  5. How does a parachute help a skydiver land gently? think about it

  6. Which falls faster, a large raindrop or a small drizzle drop? in the text

Words to know

gravity
the pull that draws objects toward the earth
resistance
a force that works against motion
balanced
equal in strength, so neither side wins
terminal
final, or the last stage reached
drizzle
very light, fine rain
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One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 226 words · Flesch-Kincaid grade 4.2

A raindrop can fall from a cloud that is far above the tallest buildings. If nothing slowed it down, gravity would keep making it faster and faster. A drop reaching the ground would hit like a tiny bullet. But real raindrops tap gently on umbrellas. The reason is air. Air pushes back on anything moving through it.

When a drop starts to fall, it moves slowly, and the air barely notices it. Gravity pulls it down, and it speeds up. As its speed grows, the air pushes back harder. The drop has to shove more air out of its way every second. This push is called air resistance, or drag. It points upward, against the motion.

Soon the drop reaches a speed where the upward push of the air equals the downward pull of gravity. The forces are balanced. The drop stops gaining speed and falls at a steady rate. This steady speed is called terminal velocity.

Different objects have different terminal velocities. A large raindrop falls faster than a small drizzle drop. That is why heavy rain falls faster than mist. A skydiver can change it too. Spreading out the arms and legs gives the air more to push on. A parachute gives it far more. This lowers the steady speed for a safe, gentle landing. Air resistance is a kind of built-in brake.

▲ This passage · 255 words · Flesch-Kincaid grade 7.7

A raindrop can fall from a cloud that sits well above the tops of the tallest buildings. If nothing slowed it down, gravity would keep making it go faster and faster, and a drop arriving at the ground would hit like a tiny bullet, but in real life, raindrops tap against umbrellas gently. The reason is air, which pushes back against anything that moves through it.

When the drop first begins to fall, it moves slowly, and the air barely notices it, but gravity pulls it downward, and the drop speeds up. As its speed grows, the air pushes back harder, because the drop has to shove more air out of its way every second. This opposing push is called air resistance, or drag, and it points upward, against the direction of the motion.

Soon the drop reaches a speed where the upward push of the air equals the downward pull of gravity, and because the forces are balanced, the drop stops gaining speed and falls at a steady rate. This steady speed is called terminal velocity.

Terminal velocity is different for different objects. A larger raindrop falls faster than a small drizzle drop, which is why heavy rain falls faster than mist. A skydiver can change it too. Spreading out the arms and legs gives the air more to push against, and a parachute gives it far more, which brings the steady speed down to a safe, gentle landing. Air resistance is not just an obstacle. It is a kind of built-in brake.

■ Harder · 257 words · Flesch-Kincaid grade 8.2

A single raindrop may begin its journey in a cloud that hangs far above the tops of the tallest buildings. If nothing resisted its descent, gravity would keep accelerating it faster and faster, and a drop arriving at the ground would strike with the force of a tiny bullet. In reality, raindrops tap gently against umbrellas. The explanation is air, which pushes back against anything that moves through it.

When the drop first begins to fall, it travels slowly, and the air barely notices it. Gravity pulls the drop downward, and it accelerates. As its speed increases, however, the air pushes back with growing strength, because the drop must shove aside more air every second. This opposing push is called air resistance, or drag, and it acts upward, against the direction of motion.

Before long, the drop reaches a speed at which the upward push of the air exactly equals the downward pull of gravity. The forces are then balanced, so the drop stops gaining speed and falls at a steady rate, known as terminal velocity.

Terminal velocity differs from one object to another. A large raindrop falls faster than a fine drizzle drop, which is why a downpour descends more quickly than mist. A skydiver can alter it as well. Spreading the arms and legs gives the air more to push against, and a parachute gives it vastly more, reducing the steady speed to one that permits a safe, gentle landing. Air resistance is not merely an obstacle. It is a kind of built-in brake.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put gravity, resistance, balanced, terminal and drizzle on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 3 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 3 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "Why a Falling Raindrop Stops Speeding Up"?

It was written for 8th grade. It has 255 words and works out to a Flesch-Kincaid grade level of about 7.7. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 4 ask for something the text says directly and 2 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 3 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

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