### What is the difference between a base unit and a derived unit?

Base units are defined units based on specific objects or events in the physical world. Derived units are defined by combining base units.

### You live 6 kilometers from your school. How many meters do you live from school?

6 km x 1000 m/km = 6000 m

### Explain in terms of density why a grocery bag containing all canned goods is harder to lift than a grocery bag containing all paper goods

Canned goods are more dense than paper goods. They have more mass per unit volume. Thus, for the same volume, the canned goods have more mass than the paper goods. The greater mass is more difficult to lift.

### How can you obtain an object's volume if you know its density and its mass?

Answers may vary. Students should note that density is defined as the mass of an object divided by its volume. Thus, algebraically, you can determine that an object's volume is equal to its mass divided by its density.

### How many significant digits are there in 6.023 x 1023 molecules?

There are four significant digits in 6.023 x 1023 molecules.

### You calculate that your semester average in history is 97.5. When you get your report card, your average is 96. What was the percent error of your calculation?

1.6%; Solution: percent error = error/accepted value x 100%, percent error = (97.5 - 96)/96 x 100% = 1.5625% = 1.6%

### You calculate that 213,000 m/s is the answer to a problem. What can you conclude about your answer?

It has three significant figures.

### Poor precision in scientific measurement may arise from

both human error and the limitations of the measuring instrument.

### Three different people weigh a standard mass of 2.00 g on the same balance. Each person obtains a reading of 7.32 g for the mass of the standard. These results imply that the balance that was used is ____.

precise

### Nancy is asked to use her calculator to find the volume of a cylindrical canister that has a radius of 10.55 cm and a height of 12.56 cm. Which answer is the most accurate? Volume of a cylinder can be calculated using the following equation: V=πr2h

4392 cm3

### The three most common data patterns seen are:

Proportionality, linearity and inverse proportionality

### base unit

A defined unit in a system of measurement that is based on an object or event in the physical world and is independent of other units.

### precision

Refers to how close a series of measurements are to one another; precise measurements show little variation over a series of trails, but may not be accurate.

### significant figure

The number of all known digits reported in measurements, plus one estimated digit.