Key Concepts

A submerged object displaces a volume that liquid same to the volume the the object.One milliliter (1 mL) the water has actually a volume that 1 cubic centimeter (1cm3).Different atoms have different sizes and also masses.Atoms top top the routine table space arranged in order according to the number of protons in the nucleus.Even despite an atom might be smaller sized than another atom, it could have more mass.The massive of atoms, your size, and how they space arranged identify the thickness of a substance.Density equals the fixed of the object separated by that is volume; D = m/v.Objects through the exact same mass however different volume have different densities.

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Summary

Students usage the water displacement method to uncover the volume of various rods the all have the very same mass. They calculate the density of every rod, and also use the characteristic thickness of each product to recognize all five rods. Then students consider the relationship in between the mass, size, and also arrangement of atom to explain why different rods have various densities. Students will certainly be briefly introduced to the periodic table.

Objective

Students will have the ability to explain the materials have actually characteristic densities due to the fact that of the various mass, size, and also arrangement of their atoms. College student will have the ability to use the volume displacement method to uncover the volume of one object.

Evaluation

Download the student task sheet, and also distribute one per student once specified in the activity. The activity sheet will serve together the “Evaluate” ingredient of every 5-E lesson plan.

Safety

Make sure you and also your students wear correctly fitting goggles.

Materials for Each Group

Set the 5 various rods the all have the exact same massGraduated cylinder, 100 mLWater in a cupCalculator

Notes around the materials:

For this lesson you will need a set of five solid rods, each v the exact same mass, same diameter, however a different volume. Each rod is do of a various material. Over there are numerous versions of these rods available from various suppliers. This activity uses the same Mass Kit indigenous Flinn clinical (Product #AP4636) but can be adapted to any collection of same mass rods. Due to the fact that there are only five samples in the same Mass kit, you might need two kits so that each team can occupational with a sample.

This chart will assist you recognize each rod. Carry out not expose this information to the students. Lock will discover the identification of every rod and also the train station relationship in between the density and also the size of each rod later on in this lesson.

Table 1. Physics properties for solid cylinder unkowns.SampleMaterialApproximate density (g/cm3)Relative lengthSmallest metalShiny gray metalDark grayTall off-whiteTallest white
Brass7.5shortest
Aluminum3.0
PVC1.4
Nylon1.1
Polyethylene0.94longest

Engage

Show students 5 rods that have actually the same mass however different volumes.

Show student the 5 rods and explain the they all have actually the very same mass. Then hold up the longest, middle-sized, and shortest rods and also remind students the they have the very same mass.

Ask students to make a prediction:

Which pole is the many dense? the very least dense? In between?

Students may reason that since the massive of each rod is the same, the volume of every rod must have actually something to execute with the density. Some might go for this reason far regarding say that the rod with the the smallest volume must have the greatest density, since the very same mass is packed right into the the smallest volume. Or the the rod v the largest volume must have actually the lowest density, because the same mass is spread out out end the largest volume.

Tell college student that like the cubes in the previous activity, lock will require to understand the volume and mass of every of the samples. Lock will also calculate the density of each sample and use this worth to number out which product each pole is do of.

Show an animation and demonstrate exactly how to measure volume using the water displacement method.

Project the animation Water Displacement.

Play the animation as you show the water displacement an approach using a cup of water, a graduated cylinder, and a rod, the means students will execute in the activity. Use the dark gray plastic sample so the students have the right to see the better.

Volume

Demonstrate what college student will carry out by putting water from a cup into a 100-mL graduated cylinder until it will a elevation that will cover the sample. This is the “initial water level.”

Tell students the the surface of water in a tube may not be completely flat. Instead, the surface may curve in a shallow U-shape called the meniscus. As soon as measuring, review the line simply at the bottom of the meniscus.

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Tilt the i graduated cylinder and also slowly on slide the sample right into the water. Organize the i graduated cylinder upright. Document the level of the water. Point out the this is the “final water level.”

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Tell students the you want to uncover out exactly how much the water level changed. Subtract the initial water level from the final water level to find the volume of the rod.

Volume that sample = final water level − early water level.

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Explore

Have students calculate the density of five different rods and use the characteristic residential property of thickness to correctly recognize them.

Note: The densities because that the three plastics space similar, for this reason students have to be really careful as soon as measuring your volume utilizing the water displacement method. Also, it is an overwhelming to measure up the volume that the the smallest rod. Provide students a hint the it is between 1.5 and also 2.0 mL.

Question come investigate

Can you use density to identify all 5 rods?

Materials because that each group

Set of five different rods the all have the exact same massGraduated cylinder, 100 mLWater in a cupCalculator

Teacher preparation

Use a irreversible marker to mark the 5 rods through letters A, B, C, D, and E. Keep track of i m sorry letter corresponds to which sample there is no letting students know. If you room using two or an ext sets that rods, be sure to note each sample the the same product with the exact same letter. After ~ a team finds the volume the a sample, they have to then pass that sample to an additional group till all teams have discovered the volume the all 5 rods. For the longest sample, which floats, students can use a pencil to gently push the sample just beneath the surface of the water to measure up its complete volume.

Procedure

VolumePour sufficient water from your cup into the graduated cylinder to reach a elevation that will cover the sample. Read and record the volume. Slightly tilt the graduated cylinder and carefully ar the sample into the water. Place the i graduated cylinder upright top top the table and also look at the level that the water. If the sample floats, use a pencil to gently push the top of the sample just under the surface ar of the water. Record the variety of milliliters for this final water level.

Find the quantity of water displaced by subtracting the initial level that the water indigenous the final level. This volume equals the volume that the cylinder in cm3.

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Record this volume in the graph on the activity sheet.Remove the sample by pouring the water back into her cup and taking the sample the end of your i graduated cylinder.DensityCalculate the thickness using the formula D = m/v. Document the density in (g/cm3).Trade samples v other groups until you have actually measured the volume and calculated the thickness of all five samples. Table 2. Volume, mass, and also density because that unknowns A–HSampleInitial water level (mL)Final water level (mL)Volume the the rods (cm3)Mass (g)Density (g/cm3)ABCDE
15.0
15.0
15.0
15.0
15.0
Identify the samplesCompare the values for density you calculated come the values in the chart. Then compose the letter name for each sample in the chart.

Note: The densities student calculate may not be precisely the same as the offered densities in the chart. As students room working, inspect their worths for volume come be certain that they room using the difference in between the final and initial water levels, not simply the last level.

Table 3. Volume, mass, and also density for unknowns A–HMaterialApproximate thickness (g/cm3)Sample (Letters A–E)BrassAluminumPVCNylonPolyethylene
8.8
2.7
1.4
1.2
0.94

Discuss whether students’ worths for thickness support their predictions native the beginning of the lesson.

Discuss student values for thickness for each of the samples. Point out that various groups might have different values because that density, yet that many of the values room close to the values in the chart.

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Ask students:

Each group measured the volume that the exact same samples. What room some factors that groups can have different values for density?Students should realize that little inaccuracies in measure up volume have the right to account for differences in thickness values. Another reason is that the i graduated cylinder, itself, is not perfect. So over there is always some skepticism in measuring.

Remind students the in the beginning of the class they do a prediction about the thickness of the small, medium, and also long sample. Student should have predicted the the longest cylinder has actually the shortest density, the shortest cylinder has the highest density, and the middle is what in between.

Ask students:

Was her prediction about the density of these 3 samples correct? have actually students look at at your chart through the worths for mass, volume, and density because that each cylinder. Have actually them look because that a relationship between the volume and the density. Students need to realize that the shortest cylinder has actually the best density and the longest cylinder has actually the shortest density. Is it fair to say that if two samples have the very same mass that the one v the bigger volume will have actually a reduced density? Yes.Why?Because the samples have actually the very same mass, their volumes will provide you an idea about their densities according to the equation D = m/v. If a bigger number because that volume is in the denominator, the thickness will it is in lower. Is it same to say that the one with the smaller sized volume will have actually a greater density? Yes.Why?If a smaller number because that volume is in the denominator, the density will be higher.