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Soft Landings: Kinetic Energy From Liftoff to Touchdown

Grade 8 kinetic energy practice: use a rocket's flight log, parachute tests and a bar graph to compare how speed and mass change kinetic energy.

Grade 8ScienceInteractive · Printable

Aligned toMS-PS3-1

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
11 questions
Classroom-ready

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 tables and a bar graph to show that kinetic energy grows with the square of speed and in step with mass.
Students calculate kinetic energy with KE = ½ × m × v² and compare it with a safety limit.
Students argue from data which recovery plan lowers a rocket's landing energy more.

How to use

Work the first flight-log row together so students see the formula with units. Calculators help; let students check each other's sort in pairs before the open response.

Curriculum

NGSS standard covered

MS-PS3-1

Use graphs and tables to show how kinetic energy depends on an object's mass and its speed.

Preview

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Soft Landings: Kinetic Energy From Liftoff to Touchdown

Use a flight log, a recovery test and a bar graph to see how speed and mass set a rocket's kinetic energy.

The Swift's flight log

Read the club notes and study Table 1. Use KE = ½ × m × v² where a question asks you to calculate.

Launch Day at Cutler Field

1On the second Saturday of every month, the Prairie Wind Rocketry Club launches model rockets from a mowed hayfield outside town. Each rocket climbs fast, slows down, tips over at its highest point and falls back. A small charge then pops out a parachute or a streamer, so the rocket drifts down instead of crashing. A hard landing can crack a fin or crumple the nose cone, and fixing a rocket can take weeks. This year the club's safety officer, eighth grader Wren Okafor, wants to use kinetic energy to compare landings. Kinetic energy is the energy an object has because it is moving. The club advisor, Mr. Haruki Delacroix, gave the members the formula KE = ½ × m × v², with the mass m in kilograms (kg), the speed v in meters per second (m/s) and the kinetic energy in joules (J).

2The club's rocket called the Swift carries a small flight computer that records its speed many times each second. Once the motor burns out, its fuel is used up, so the Swift's mass stays at 0.20 kg for the rest of the flight. Table 1 shows six moments from one flight, starting at motor burnout.

3Wren also ran a recovery test. The Swift was launched four times, each time with a different recovery device, and the flight computer recorded its steady speed during the last few meters before touchdown. Table 2 shows the results. After looking at the cracked fins from past launches, the club set a landing rule: a rocket may fly only if its landing kinetic energy is 2.0 J or less.

4The club also compared four of its rockets, including the Swift. Each rocket has a motor chosen so that it reaches about 40 m/s at burnout. Their masses are different, so their kinetic energies at burnout are different too. The bar graph shows these energies.

5Next month the club wants to add a 0.05 kg camera to the Swift, which would make its total mass 0.25 kg after burnout. Two plans are on the table. In Plan A, the Swift gets a larger parachute, and a test drop showed it would land at 3 m/s. In Plan B, the Swift keeps its medium parachute; because the rocket is heavier, a test drop showed it would land at 4.5 m/s.