Printable worksheet

← Back to the Buoyancy Calculator

In the print window, choose “Save as PDF” as the printer (or print it on paper). Seed 1 rebuilds this exact sheet.

Buoyancy worksheet

Grades 8–9

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- Calculate: Will it float?
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Mass of the object (m): 80 kg
- Total volume of the object: 100 L
- Gravity (g): Mars: 3.71 m/s²
Find: Fraction of volume submerged
Answer
2.
Problem 2.
- Calculate: Buoyant force
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Submerged volume (V): 36 L
- Gravity (g): Moon: 1.62 m/s²
- Show force in: Newtons (N)
Find: Buoyant force
Answer
3.
Problem 3.
- Calculate: Will it float?
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Mass of the object (m): 50 kg
- Total volume of the object: 70 L
- Gravity (g): Earth: 9.80665 m/s² (standard)
Find: Fraction of volume submerged
Answer
4.
Problem 4.
- Calculate: Will it float?
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Mass of the object (m): 78 kg
- Total volume of the object: 72 L
- Gravity (g): Mars: 3.71 m/s²
Find: Fraction of volume submerged
Answer
5.
Problem 5.
- Calculate: Buoyant force
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Submerged volume (V): 32 L
- Gravity (g): Mars: 3.71 m/s²
- Show force in: Kilonewtons (kN)
Find: Buoyant force
Answer
6.
Problem 6.
- Calculate: Will it float?
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Mass of the object (m): 60 kg
- Total volume of the object: 110 L
- Gravity (g): Custom value
- Custom gravitational acceleration: 11.4 m/s²
Find: Fraction of volume submerged
Answer
7.
Problem 7.
- Calculate: Will it float?
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Mass of the object (m): 76 kg
- Total volume of the object: 90 L
- Gravity (g): Custom value
- Custom gravitational acceleration: 7 m/s²
Find: Fraction of volume submerged
Answer
8.
Problem 8.
- Calculate: Buoyant force
- Fluid: Seawater: 1,025 kg/m³ (typical)
- Submerged volume (V): 54 L
- Gravity (g): Mars: 3.71 m/s²
- Show force in: Kilonewtons (kN)
Find: Buoyant force
Answer
9.
Problem 9.
- Calculate: Buoyant force
- Fluid: Fresh water: 997 kg/m³ (typical, 25 °C)
- Submerged volume (V): 48 L
- Gravity (g): Custom value
- Custom gravitational acceleration: 6 m/s²
- Show force in: Newtons (N)
Find: Buoyant force
Answer
10.
Problem 10.
- Calculate: Will it float?
- Fluid: Seawater: 1,025 kg/m³ (typical)
- Mass of the object (m): 55 kg
- Total volume of the object: 100 L
- Gravity (g): Earth: 9.80665 m/s² (standard)
Find: Fraction of volume submerged
Answer

Answer key: Buoyancy worksheet

1. Fraction of volume submerged: 80.24%
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the surface gravity of Mars
  $g$ $= 3.71 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $100 L \times 0.001$ $= 0.1 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{80}{0.1}$ $= 800 kg/m³$
5. Find the object's weight: its mass times gravity
  $80 \times 3.71$ $= 296.8 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $997 \times 0.1 \times 3.71$ $= 369.887 N$
7. It floats, so the share under water is the object's density divided by the fluid's
  $\frac{800}{997}$ $= 80.240722%$
2. Buoyant force: 58.15 N
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the surface gravity of the Moon
  $g$ $= 1.62 m/s²$
3. Change submerged volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $36 L \times 0.001$ $= 0.036 m³$
4. Find the upward push: fluid density × volume below the surface × gravity. This is the weight of the fluid pushed aside (Archimedes' principle)
  $997 \times 0.036 \times 1.62$ $= 58.14504 N$
3. Fraction of volume submerged: 71.64%
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the surface gravity of Earth (standard gravity)
  $g$ $= 9.80665 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $70 L \times 0.001$ $= 0.07 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{50}{0.07}$ $= 714.285714 kg/m³$
5. Find the object's weight: its mass times gravity
  $50 \times 9.80665$ $= 490.3325 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $997 \times 0.07 \times 9.80665$ $= 684.406104 N$
7. It floats, so the share under water is the object's density divided by the fluid's
  $\frac{714.285714}{997}$ $= 71.643502%$
4. Fraction of volume submerged: 100%
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the surface gravity of Mars
  $g$ $= 3.71 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $72 L \times 0.001$ $= 0.072 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{78}{0.072}$ $= 1,083.333333 kg/m³$
5. Find the object's weight: its mass times gravity
  $78 \times 3.71$ $= 289.38 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $997 \times 0.072 \times 3.71$ $= 266.31864 N$
7. It is denser than the fluid, so it sinks and goes fully under
  $Submerged fraction$ $= 100%$
8. Find how heavy it feels underwater: its weight minus the upward push
  $289.38 - 266.31864$ $= 23.06136 N$
5. Buoyant force: 0.12 kN
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the surface gravity of Mars
  $g$ $= 3.71 m/s²$
3. Change submerged volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $32 L \times 0.001$ $= 0.032 m³$
4. Find the upward push: fluid density × volume below the surface × gravity. This is the weight of the fluid pushed aside (Archimedes' principle)
  $997 \times 0.032 \times 3.71$ $= 118.36384 N$
5. Change the answer to kN, the unit you picked: divide by 1,000
  $\frac{118.36384}{1,000}$ $= 0.118364 kN$
6. Fraction of volume submerged: 54.71%
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the gravity value you entered
  $g$ $= 11.4 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $110 L \times 0.001$ $= 0.11 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{60}{0.11}$ $= 545.454545 kg/m³$
5. Find the object's weight: its mass times gravity
  $60 \times 11.4$ $= 684 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $997 \times 0.11 \times 11.4$ $= 1,250.238 N$
7. It floats, so the share under water is the object's density divided by the fluid's
  $\frac{545.454545}{997}$ $= 54.709583%$
7. Fraction of volume submerged: 84.7%
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the gravity value you entered
  $g$ $= 7 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $90 L \times 0.001$ $= 0.09 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{76}{0.09}$ $= 844.444444 kg/m³$
5. Find the object's weight: its mass times gravity
  $76 \times 7$ $= 532 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $997 \times 0.09 \times 7$ $= 628.11 N$
7. It floats, so the share under water is the object's density divided by the fluid's
  $\frac{844.444444}{997}$ $= 84.69854%$
8. Buoyant force: 0.21 kN
1. Use the density of seawater (typical)
  $ρ$ $= 1,025 kg/m³$
2. Use the surface gravity of Mars
  $g$ $= 3.71 m/s²$
3. Change submerged volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $54 L \times 0.001$ $= 0.054 m³$
4. Find the upward push: fluid density × volume below the surface × gravity. This is the weight of the fluid pushed aside (Archimedes' principle)
  $1,025 \times 0.054 \times 3.71$ $= 205.3485 N$
5. Change the answer to kN, the unit you picked: divide by 1,000
  $\frac{205.3485}{1,000}$ $= 0.205349 kN$
9. Buoyant force: 287.14 N
1. Use the density of fresh water at 25 °C (typical)
  $ρ$ $= 997 kg/m³$
2. Use the gravity value you entered
  $g$ $= 6 m/s²$
3. Change submerged volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $48 L \times 0.001$ $= 0.048 m³$
4. Find the upward push: fluid density × volume below the surface × gravity. This is the weight of the fluid pushed aside (Archimedes' principle)
  $997 \times 0.048 \times 6$ $= 287.136 N$
10. Fraction of volume submerged: 53.66%
1. Use the density of seawater (typical)
  $ρ$ $= 1,025 kg/m³$
2. Use the surface gravity of Earth (standard gravity)
  $g$ $= 9.80665 m/s²$
3. Change object volume to m³, the standard unit the formula uses (1 L = 0.001 m³)
  $100 L \times 0.001$ $= 0.1 m³$
4. Find the object's average density: its mass divided by its volume
  $\frac{55}{0.1}$ $= 550 kg/m³$
5. Find the object's weight: its mass times gravity
  $55 \times 9.80665$ $= 539.36575 N$
6. Find the upward push if it were fully under: fluid density × its whole volume × gravity
  $1,025 \times 0.1 \times 9.80665$ $= 1,005.181625 N$
7. It floats, so the share under water is the object's density divided by the fluid's
  $\frac{550}{1,025}$ $= 53.658537%$