Name ______________________ Class __________________ Date _______________Physical Science Units and Measurement

Density practice problems #1 – Answer Key

For full credit: Show your work and place a box around your final answer – be sure to include units

1. A block of wood has a mass of 500 g and a volume of 750 cm3. What is the density of the wood in g/cm3?

2. A piece of lead has a mass of 0.5 kg and a volume of 76.2 cm3. What is the density of lead in g/cm3?

3. What is the volume of 4.5 kg of butter? (density = 0.86 g/cm3)

To solve this problem, you need to follow the 5-step problem solving method:

Step 1: Identify all of the knowns in the problem

Knowns:

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m = 500g

V = 750cm3

Step 2: Identify all of the unknowns in the problemUnknowns:

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ρ =?

Step 3: Decide on an equation needed to solve the problem. Write it .

Equation:

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ρ =m

V

Step 4: Substitute all numbers with units into equation.

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ρ =mV

ρ =500g

750cm3

Step 4: Solve the equation. Don’t forget units on all numbers!

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ρ =0.67g

cm3

To solve this problem, you need to follow the 5-step problem solving method. This one looks like this.

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m = 0.5kg

m = 500g

V = 76.2cm3

ρ = ?

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ρ =mV

ρ =500g

76.2cm3

ρ = 6.56g

cm3

Note: Mass had to be converted to g from kg first.Also, all the equal signs are lined up vertically.

Name ______________________ Class __________________ Date _______________Physical Science Units and Measurement

4. What is the mass of 1500 cm3 of ice? (density = 0.92 g/cm3)

5. What is the mass of a block of pine with the following dimensions: 5 cm x 5 cm x 10 cm (density = 0.710 g/cm3)

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m = 4.5kg

m = 4500g

ρ = 0.86g

cm3

V = ?

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ρ =m

V

V =m

ρ

V =4500g

0.86g

cm3

V = 5232cm3

Note: We had to solve for volume, so we solved the equation for V first.

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V =1500cm3

ρ = 0.92g

cm3

m = ?

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ρ =m

Vm = ρ ⋅V

m = 0.92g

cm3⋅1500cm3

m =1380g

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l = 5cm

w = 5cm

h =10cm

V = ?

V = l ⋅w ⋅h

V = 5cm ⋅5cm ⋅10cm

V = 250cm3

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V = 250cm3

ρ = 0.710g

cm3

m = ?

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ρ =m

Vm = ρ ⋅V

m = 0.710g

cm3⋅250cm3

m =177.5g

Note: We had to solve for volume, so we solved the equation for V first.