WorksheetPremium

The Gravity Survey Robot: Finding a Hidden Cave

Grade 8 gravity practice: a robotics team's robot carries a gravity meter over a park, and students argue that gravity attracts and depends on mass.

Grade 8ScienceInteractive · Printable

Aligned toMS-PS2-4

Buy this worksheet: $1.50

Or unlock every Premium worksheet with Premium

PrintUnlock to print

Answer keyUnlock to see answers

Assign to classUnlock to assign with a class code

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, Circle the answer, Sorting, Short answer

About this worksheet

What students practice

Students use gravity survey data to argue that the pull of gravity depends on the mass of nearby objects.
Students use historical evidence to argue that gravity is an attractive force between objects with mass.

How to use

Read the survey report together and make sure students understand what a negative reading means before they start. The final argument works well as a short written response.

Curriculum

NGSS standard covered

MS-PS2-4

Argue from evidence that gravity is attractive and depends on the masses of the objects.

Preview

OwlSheets.com

Name Date

The Gravity Survey Robot: Finding a Hidden Cave

Argue from survey data and a mountain test that gravity attracts and depends on mass.

Part 1: The survey data

Read the survey report and study the table. Then answer the questions.

Survey Report: What Is Under Larkin Park?

1The robotics team at Kestrel Ridge Middle School built a delivery robot that carries library books and lab supplies across campus. This spring, a small sinkhole opened at the edge of Larkin Park, next to the school, where the city plans to build a new playground. The rock under this part of the region is limestone, which slowly dissolves in groundwater and can leave hidden caves. City geologist Dr. Ingrid Halloran borrowed a gravity meter, a very sensitive instrument that measures tiny changes in the pull of gravity on a small test mass inside it. She asked team members Bodhi Achterberg and Linnea Okoro to program their robot to carry the meter along straight survey lines, stopping every 10 m so the meter could take a reading while the robot sat still.

2The meter gives each reading in microgals (µGal), compared with the average for the whole park. One µGal is about one billionth of Earth's usual pull at the surface. A negative reading means the pull is slightly weaker than the park average at that spot, and a positive reading means it is slightly stronger. Readings at the same spot repeat within about 5 µGal. The robot ran each line three times on different days, and the table shows the averages.

3Line A crosses the area near the sinkhole. Line B crosses the north end of the park, where old well records describe a band of dark rock. After the survey, the city drilled one hole at the 30 m station on each line. On line A, the drill broke into an open, air-filled space about 9 m below the surface. On line B, it brought up basalt, a rock with more mass in each cubic centimeter than the limestone around it. Nobody had known exactly where the band of basalt ran until the survey.

4The idea behind the survey is old. In 1774, scientists hung plumb lines, small weights on strings, on the north side and the south side of Schiehallion, a large, steep mountain in Scotland. They compared the direction of each string with the positions of stars. On each side, the string hung very slightly toward the mountain, by less than one hundredth of a degree.