Chapter 1 –Science and Measurement

1.1 -- Time and Distance

Two fundamental properties of the universe: time and distance

What is time? – 1. Identify a particular moment

– Ex: 12:00 a.m. on December 31st

– 2. Interval of time

– Ex: The time it takes for someone to run 100 meters

http://www-math.cudenver.edu/~wcherowi/clockar.html

Time is measured in seconds for most science purposes. Other units for time are hours, days, and years.

Conversion of seconds1. Separate the total time into the amount of time

in each unit

2. Convert each separate quantity of time to seconds

3. Add all the seconds together

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• Ex: Convert 1:26:31.25 to second

• 1. Separate each unit– 1 hour; 26 minutes; 31.25 seconds

• 2. Convert each unit– 1 hr x (3,600 sec) = 3,600 sec– (1 hr)– 26 minutes x (60sec) = 1,560 seconds

(1 min)• 3. Add together

– 3,600 + 1,560 + 31.25 = 5,191.25 seconds

Distance describes how far it is from one point to another. It is measured in units of length. Without units, distance measurements are meaningless.

Two common systems of units are used for measuring distance.– 1. English system (in, ft, mi)– 2. Metric system (mm, cm, m, km)

Measurement Systems

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Practice reading ruler

Purpose of units: So people could communicate amount to each other.

Almost all fields of science use metric units because they are easier to work with. The metric system is based on factors of 10.

1.2 –Investigations and Experiments Science is about figuring out cause and

effect relationships. A series of one or more experiments that

helps us answer a question is called an investigation.

An experiment is any situation we set up to observe what happens.

Measurements are observation that can be recorded.

Experiments usually start with a question.

Learning new information is the most important things scientists do. Science is a way of collecting information to help solve problems. Experiments provide evidence.

Scientific evidence is any observation that can be repeated with the same results.

The scientific method is a process that is used to gather evidence. People use the scientific method everyday without realizing it.

Steps to the scientific method: 1. Ask a question based on observation 2. Form a hypothesis 3. Design and conduct an experiment 4. Collect and analyze data 5. Make a conclusion 6. Communicate your results

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A research question is a question that is solved through investigation.

A hypothesis is a prediction that can be tested using an experiment.

Factors that affect the results of an experiment are called variables. You can think of variables in terms of cause and effect.

The variable you change -- experimental variable. The variables that are kept constant -- control variables. When you change 1 variable and control all of the others, it is a controlled experiment. This is the preferred way to get reliable scientific evidence.

Each time an experiment is run it is called a trial. For accurate results, each trial must be as close to the other collected data as possible.

Experimental technique is how you perform the experiment. Each trial needs to be done the same way.

The procedure is a collection of all the techniques you use during the experiment.

Scientific discoveries and inventions must always be able to be tested by someone else.

1.3 -- Speed

The speed of an object is a measure of how fast the objects gets from one place to another.

Remember, objects at rest have a speed of zero.

Determining speed requires two things:• 1. distance traveled

• 2. time taken

Speed is calculated by taking the distance traveled divided by the time taken.

Units of speed are a ratio of distance units over time. m/sec or miles/hr

Formula of speed: v = d t v = speed d = distance t = time