Measurement Homework

Careful measurement underlies all of science. In this lab, you are going to carry out some simple yet important measurements of the mass, volume, and density for some objects.

You may find the following formulas useful:

· Volume of a block=

· Volume of a cylinder=

The radius is half the diameter

· Volume of a sphere =

The radius is half the diameter

· Density = mass/Volume

Note that in the formulas above the quantities you measure directly like length, radius, mass, etc. are denoted in italics while the quantities that are derived, like volume or density are written in regular type. One possible exception is that Volume can also be measured directly by placing the object to be measured in a graduated cylinder containing a known volume of water and measuring the volume change.

1. Measure the mass and dimensions of each of the following. Be sure to tell the material of which the object is made. Use the electronic scale to measure the mass. Use the ruler to measure “straight” dimensions and use the calipers to measure the diameters of the cylinder and the sphere. Show only significant figures.

Object	material	mass	length	width	height	diameter
a. block
b. cylinder
c. sphere

2. Calculate the volume and density for each of your objects. Show your calculations and use of significant digits.

Object	mass	Volume	Density
a. block
b. cylinder
c. sphere

3. Measure the mass of one object using both the balance and measure its volume by using displacement. Calculate densities from each pair of masses and volumes. Show the use significant figures.

Object

mass/scale

mass/balance

Volume/calculated

Volume/measured by displacement

a. Which one you would choose as most accurate, both from the point of view of accuracy of measurement as well as significant figures. Discuss your reasons

4. Discuss the following:

a. Explain the difference between mass and weight

b. Which does the scale measure? Which does the balance measure? Explain.

c. Why does the displacement method work for measuring the volume of some objects? Would it work for all objects?