Worksheet

Delivery Robot Test Runs: Load, Speed and Kinetic Energy

Grade 8 kinetic energy practice: pick fair pairs from a robotics team's mixed test runs to separate the effects of mass and speed, then set a safe speed rule.

Grade 8ScienceInteractive · Printable

Aligned toMS-PS3-1

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What’s included

Single worksheet
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1 NGSS standard
Printable answer key
9 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 choose pairs of test runs that isolate the effect of mass or of speed on kinetic energy.
Students use a bar graph and a table to show that kinetic energy grows with mass and with the square of speed.
Students use the kinetic energy relationship to judge which robot settings meet a safety limit.

How to use

Have students circle the runs that share a mass or a speed in the table before they read the bar graph, then discuss the safety rule as a class.

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.

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Delivery Robot Test Runs: Load, Speed and Kinetic Energy

Sort out the effects of mass and speed from a robotics team's mixed test runs.

The test runs

Read the team notes, then use the table and the bar graph.

Team Notes: A Robot for the Hallways

1The Ridgecrest Middle School robotics team is building a robot that rolls down the hallways carrying library books and supplies to classrooms. Before it can drive near students, the principal wants proof that it is safe. Team captain Oluwaseun Park explained that the danger depends on the robot's kinetic energy, the energy it has because it is moving, since that is the energy a bumper has to soak up if the robot runs into something.

2Coach Saoirse Banerjee set up a test course in the gym, ending at a padded wall. The robot's body has a mass of 10 kg, and team member Mireille Kovac loaded it with boxes of books to change the total mass. A pair of timing gates near the end of the course measured the robot's speed. The team's software then worked out the kinetic energy with the formula KE = ½ × mass × speed², using mass in kilograms and speed in meters per second to give energy in joules (J). In the formula, speed² means the speed multiplied by itself, so a speed of 2.0 m/s gives 2.0 × 2.0 = 4.0. Each run was repeated three times, and the results are averages. Nobody stood on the course during a run, and the robot never went faster than a jogging pace.

3The team tried different loads and speeds on different days, so the runs in the table are not in any special order. Some runs changed the mass, some changed the speed, and some changed both. Mireille pointed out that a fair comparison needs two runs that differ in only one way, so the team has to choose its pairs with care before drawing any conclusion.

4The hallways at Ridgecrest are crowded between classes, so the team plans to run the robot only while classes are in session. Even then, a student could step out of a classroom door at any moment. Oluwaseun wants the robot to carry as many books as possible on each trip, while Mireille wants it to move fast enough to finish every delivery before lunch. The test runs were planned to help the team balance load and speed.

Test Runs
Run	Total mass (kg)	Speed (m/s)
A	10	1.0
B	20	1.0
C	10	2.0
D	20	2.0
E	30	1.0
F	10	3.0

Which two runs should the team compare to see how mass alone affects kinetic energy?

A. Runs B and C
B. Runs A and E
C. Runs D and F
D. Runs A and C

Compare runs A and E. Run E has 3 times the mass of run A at the same speed.

The kinetic energy in run E is times the kinetic energy in run A.

Compare runs A and F. Run F has 3 times the speed of run A with the same mass.

The kinetic energy in run F is times the kinetic energy in run A.

Which statement fits all of the runs?

A. Kinetic energy grows in step with the mass, but with the square of the speed.
B. Kinetic energy depends on the speed, and the load makes little difference.
C. Kinetic energy grows with the square of the mass, but in step with the speed.
D. Kinetic energy grows in step with the mass and in step with the speed.

Start from run A. Use the bar graph to decide which change added more kinetic energy.

A. Both changes gave the same energy, 10 J each time.
B. Doubling the mass: the energy went from 5 J to 40 J.
C. Doubling the speed: the energy went from 5 J to 20 J.
D. Doubling the mass: the energy went from 5 J to 20 J.

Setting a safe speed rule

Use the formula in paragraph 2, the table and the bar graph.

The team has not tested a 20 kg robot at 3.0 m/s.

Predict its kinetic energy. J

Safety rule: The robot's foam bumper can safely soak up 20 J. The principal will allow only settings that give the robot a kinetic energy below 20 J.

Sort each robot setting by the safety rule.

30 kg at 1.0 m/s10 kg at 2.5 m/s40 kg at 0.5 m/s20 kg at 2.0 m/s15 kg at 1.0 m/s14 kg at 2.0 m/s

Below 20 J: allowed	Above 20 J: not allowed

The team wants a heavier load to have the same kinetic energy as run C. Which setting does that?

A. 20 kg at 1.0 m/s
B. 20 kg at 1.5 m/s
C. 40 kg at 0.5 m/s
D. 40 kg at 1.0 m/s

The robot now drives with a total mass of 24 kg at 1.0 m/s. Oluwaseun suggests carrying half the mass (12 kg total) at twice the speed (2.0 m/s) so deliveries go faster. He says, "Halving the mass and doubling the speed cancel out, so it is just as safe." Do you agree? Write a claim, give evidence from the runs, and explain your reasoning. Then say whether his plan meets the safety rule.