Quiz & test questions Grade 9 Engineering & Design

Dunhaven Water Storage and Distribution: A Unit Test

A grade 9 test on a fictional water system covering tank volume, pressure from head, demand conversion, and fire-flow reserve, with choice and computation items.

Grade: Grade 9
Subject: Engineering & Design
Material: Quiz & test questions
Time: 40 min
Prep: No prep
Materials: None

Standards

HSG-MG.A.1 Common Core Math

Use geometric shapes, their measures, and their properties to describe objects (e.g., modeling a tree trunk or a human torso as a cylinder).

How this material aligns: Item 2 models the elevated tank as a cylinder to find its stored volume in gallons, the geometric-modeling of a real object this standard names.

All materials for HSG-MG.A.1 →

HSN-Q.A.1 Common Core Math

Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays.

How this material aligns: Items 3 and 5 convert head to pressure and million gallons per day to gpm, tracking units through each step as this standard requires.

All materials for HSN-Q.A.1 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will calculate tank volume, pressure from head, and demand in gpm for a water system.
Students will judge whether pressures and stored volume meet stated service and fire-flow needs.

Vocabulary

Key words: head, pressure, storage, fire flow

Teacher overview

This 40-minute unit test is worth 31 points. It checks whether students can find tank volume, turn water height into pressure, convert daily demand into gpm, and judge whether a system meets service and fire-flow needs. The test mixes two multiple-choice items, two short-answer items, and five computation items, all set in one fictional water system.

Dunhaven Water Storage and Distribution: A Unit Test — Grade 9 Engineering & Design

Name: ____________________________ Date: ______________

Assessment

Use these facts about the fictional Dunhaven Water System for every item.

The elevated tank is a cylinder 50 feet across with a water depth of 30 feet.
Cylinder volume (cu ft) = 0.785 × diameter² × depth. One cubic foot holds 7.48 gallons.
Pressure (psi) = height of water above a point (feet) × 0.433.
One million gallons per day (MGD) equals 694 gpm. The state minimum service pressure is 20 psi.

(2 points) The water pressure at a point below the tank depends most on which of these?
- A) The tank's diameter
- B) The height of water above that point
- C) The color of the pipe
- D) The time of day
(4 points) Find the volume of water in the full tank, in gallons. Use the cylinder formula, then convert to gallons.
(3 points) A home sits where the water surface is 140 feet above it. Find the water pressure at that home, in psi. Round to the nearest tenth.
(4 points) A hillside home sits where the water surface is only 55 feet above it. Find the pressure there, and state whether it meets the 20 psi state minimum.
(4 points) The system's daily demand is 1.5 MGD. Convert that demand to gpm.
(4 points) If the source fails, how long can the full tank meet demand at the gpm from item 5? Use your item 2 tank volume. Give the answer in hours, rounded to the nearest tenth.
(3 points) In one or two sentences, explain why utilities place storage tanks up high, on hills or towers.
(3 points) Which change would raise the pressure at every home below the tank?
- A) Lowering the water level in the tank
- B) Raising the water level in the tank
- C) Repainting the tank
- D) Connecting more homes
(4 points) Firefighters need 1,500 gpm for 2 hours. How many gallons is that, and how many gallons remain in the full tank afterward? Use your item 2 tank volume.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

Answer: B) The height of water above that point.
Pressure comes from the weight of water above a point, so it depends on height, not on the tank's width, color, or the time of day.
Answer: 440,385 gallons.
Volume = 0.785 × 50² × 30 = 0.785 × 2,500 × 30 = 58,875 cu ft. In gallons that is 58,875 × 7.48 = 440,385 gallons.
Answer: 60.6 psi.
Pressure = 140 × 0.433 = 60.62, which rounds to 60.6 psi.
Answer: 23.8 psi.
Pressure = 55 × 0.433 = 23.815, which rounds to 23.8 psi. Because 23.8 is greater than 20, the hillside home meets the state minimum.
Answer: 1,041 gpm.
1.5 MGD × 694 gpm per MGD = 1,041 gpm.
Answer: 7.1 hours.
440,385 gallons ÷ 1,041 gpm = 423.0 minutes. In hours that is 423.0 ÷ 60 = 7.05, which rounds to 7.1 hours.
Answer: Placing a tank up high gives the water a large height above the homes below, and that height creates pressure by gravity. The system then delivers steady pressure without running a pump every moment.
Answer: B) Raising the water level in the tank.
Raising the water level increases the height of water above each home, and pressure rises with that height.
Answer: 180,000 gallons for the fire; 260,385 gallons remain.
Fire flow = 1,500 gpm × 120 minutes = 180,000 gallons. The tank holds 440,385 gallons, so 440,385 − 180,000 = 260,385 gallons remain afterward.

Differentiation

Support

Provide the cylinder volume set up for item 2, so students carry out the multiplication rather than recalling the formula. Give a small reference card with the pressure rule and the MGD-to-gpm conversion.

Extension

Ask students to find the tank diameter that would be needed to store twice the water at the same 30-foot depth, and to explain why doubling the volume does not double the diameter.

ELL supports

Provide a labeled diagram of the tank and a home below it, with height, pressure, and gallons marked. Offer a sentence frame for item 7: "Tanks are placed high because ___, which makes pressure by ___."