1.2 Describing the Physical World Energy is how the universe changes. A fast ball has more energy than a slow ball.

1.2 Describing the Physical World Up-down, right-left, and forward-backward are three directions of space. To completely understand the motion of a ball we need to know its exact path.

1.2 Describing the Physical World Time is our reference for understanding change. As time goes on, each change causes other changes, which cause still more changes.

1.2 Mass Mass is measured in kilograms (kg). Bananas = 1000 g Cat = 5000 g Person = 55000 Motorcycle = 200,000 One gram (g) is one-thousandth of a kilogram. How many grams is each item above?

1.2 Mass For small amounts of mass, the kilogram is too large a unit to be convenient. In the laboratory you will usually measure mass with a balance. The balance displays mass in grams.

1.2 Length and Distance Distance is the amount of space between two points. Distance is measured in units of length.

1.2 Length and Distance Some of the commonly used units of length include inches, feet, miles, centimeters, kilometers, and meters.

1.2 Length and Distance The names of units in the metric system are based on multiplying by ten. Almost all fields of science use metric units because they are easier to work with.

1.2 Measuring Length For ordinary lengths you must measure in the laboratory a meter stick is the most convenient tool to use. For very small lengths, such as the size of a bacteria, scientists use measuring instruments that fit into a microscope.

1.2 Time Time has two important meanings. What time is it? How much time?

1.2 Time Units for time include: seconds minutes hours The second is the basic unit of time in both the English and metric systems.

1.2 Mixed units of time Time is often expressed in mixed units. This timer shows the time for a race as 2 hours, 30 minutes and 45 seconds.

Metric Scavenger Hunt Title and date For each question: List the object Side measuring The actual measurement with correct unit