Worksheet

Launch Day Altimeter Log: Height and Stored Energy

Grade 8 potential energy practice: use a model rocket's altimeter log to model how the rocket–Earth distance changes stored energy, then compare two rockets.

Grade 8ScienceInteractive · Printable

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Single worksheet
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1 NGSS standard
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11 questions
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Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Sorting, Short answer

About this worksheet

What students practice

Students use flight data to model how the distance between a rocket and Earth changes stored energy.
Students calculate changes in stored energy from height data and compare two systems.
Students tell apart stored energy and motion energy at different points of a flight.

How to use

Use after introducing potential energy as energy stored in a system. Have students trace the flight on the log, moment by moment, before they answer Part 1.

Curriculum

NGSS standard covered

MS-PS3-2

Model how changing the distance between interacting objects changes the potential energy stored in the system.

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Name Date

Launch Day Altimeter Log: Height and Stored Energy

Use a model rocket's flight log to model how distance from Earth changes stored energy.

Part 1: The Kestrel's flight log

Read the launch day notes and study the flight log. Then answer the questions.

Launch Day at the Sod Farm

1On the first Saturday in May, the Harlow Flats Rocket Club met at a grassy sod farm outside town for launch day. Eighth grader Kalani Brandt had built the club's newest rocket, the Kestrel, and fitted it with a small altimeter, a device that records the rocket's height above the ground several times each second. Club advisor Ms. Yevgenia Torres asked the members to use the altimeter data to model how energy is stored as the rocket moves away from Earth and back again.

2Ms. Torres explained that the rocket and Earth pull on each other even when they are not touching, so together they form a system. Potential energy is stored in this system, and the amount depends on the distance between the rocket and Earth. Near Earth's surface, Earth pulls on each kilogram with a force of about 10 N, so the energy stored compared with the ground is: stored energy (J) = mass (kg) × 10 × height (m). After its motor burns out, the Kestrel has a mass of 0.25 kg, so each meter of height adds 2.5 J.

3Ms. Torres launched the Kestrel from a launch pad at the center of the field while everyone stood well back. The motor burned for 1.5 s and pushed the rocket up to 40 m. After that, the rocket coasted upward, slowing down the whole way, until it reached its highest point. There a small charge pushed out a parachute, and the rocket drifted slowly back down. It landed in the grass about 50 s after liftoff, and Kalani downloaded the log to the club's laptop.

4Later that afternoon, the club launched the Osprey, a wider rocket with a heavier camera inside. After its motor burned out, the Osprey had a mass of 0.50 kg. Its altimeter showed that it reached a highest point of only 80 m.

5While the club packed up, member Ana Lucero tried a different system. She rubbed two plastic streamers with a wool cloth, which gave both streamers the same kind of electric charge, and hung them side by side from the launch rod. The streamers pushed each other apart without touching. When Ana pinched their ends together and let go, they sprang apart. The closer together she pinched them, the faster they sprang apart.

Kestrel Flight Log (stored energy compared with the ground)
Moment	Time (s)	Height (m)	Stored energy (J)
A: On the pad	0	0	0
B: Motor burns out	1.5	40	100
C: Highest point	6.0	160	?
D: Parachute open	8.0	140	350
E: Drifting down	25	80	200
F: Landing	50	0	0

Use the formula in paragraph 2 to find the missing value in the flight log.

At moment C, the rocket–Earth system stored J compared with the ground.

Use paragraph 3 and the flight log. At which moment was the most energy stored in the rocket–Earth system?

A. Moment D, because the parachute had just opened and was slowing the rocket
B. Moment A, because the motor still held its unburned fuel on the pad
C. Moment B, because the rocket was moving fastest when its motor burned out
D. Moment C, because the rocket and Earth were the farthest apart

Use the flight log. The rocket drifted from moment C down to moment E.

The energy stored in the rocket–Earth system went down by J.

Use the flight log. Between moment E and moment F, the rocket drifted down under its parachute for 25 s.

On average, the stored energy went down by J each second.

Which statement best describes how the stored energy changes with height in the flight log?

A. It rises in step with the height: every 40 m of height adds 100 J.
B. It depends on the time since liftoff more than on the height.
C. It rises fastest near the ground and adds less for each meter higher up.
D. It rises on the way up but follows a different pattern on the way down.

Part 2: Two rockets and two streamers

Use paragraphs 2, 4 and 5 and the flight log to answer the questions.

Use paragraphs 2 and 4.

At its highest point, the Osprey–Earth system stored J compared with the ground.

Compare the two rockets at their highest points. Which statement is correct?

A. The Osprey's system stored more energy, because the Osprey has twice the mass.
B. The two systems stored the same energy: twice the mass at half the height.
C. The Kestrel's system stored more energy, because the Kestrel flew twice as high.
D. The systems stored less there than at burnout, since each rocket stopped for an instant.

Kalani wants the Kestrel (0.25 kg) to reach a height where the rocket–Earth system stores 500 J compared with the ground.

The Kestrel would need to reach a height of m.

Use the passage and the flight log. Sort each change by what happens to the potential energy stored in the system named.

Rocket–Earth system: the Kestrel coasts from moment B to moment C.Streamer system: Ana pinches the two charged streamers closer together.Rocket–Earth system: Kalani carries the rocket at one height across the flat field.Streamer system: Ana lets go, and the streamers spring apart.Rocket–Earth system: the Kestrel drifts from moment D to moment E.Rocket–Earth system: Kalani lifts the rocket from the grass onto a 1 m tall table.

Stored energy increases	Stored energy decreases	Stored energy stays the same

10.

The rocket and Earth attract each other, but Ana's streamers repel each other. Which model fits both systems in the passage?

A. In both systems, the stored energy is held in the one object that moves.
B. In both systems, moving the two objects closer together stores more energy in them.
C. Attracting objects store more when farther apart; repelling ones, when closer.
D. In both systems, moving the two objects farther apart stores more energy in them.

11.

A club member says, "The Kestrel–Earth system stored the most energy at moment B, because that is when the rocket was moving fastest." Do you agree? Write a claim, give evidence from the flight log and paragraph 3, and explain your reasoning about what stored energy in the rocket–Earth system depends on.