Physics is about finding the simplest and least complicated explanation for things.

Transcription

1 WHAT IS PHYSICS Physics is about finding the simplest and least complicated explanation for things. It is about observing how things work and finding the connections between cause and effect that explain why things happen. Aspects of Physics 1. The Universe is defined as everything that exists. Everything in the Universe is either Matter or energy Matter is all of the stuff in the universe that has MASS! Energy is a measure of the ability to make things change. What are some ways things can change???? 1

2 2. A Natural law tells us how or why something happens the particular way it does. 2

3 Matter is all of the stuff in the universe that has MASS! MASS- is the measure of the amount of matter that makes up an object. vs. The universe is huge and complex. The only way to make sense of it is to think about only a small part at a time. A system is a group of objects, effects, and variables that are related. A variable is a factor that affects the behavior of the system. 3

4 Unit 1 Notes.notebook Observations are on the macroscopic scale when they are large enough for us to see or directly measure. EX/ Making a road wide enough for 2 cars WHAT DO WE KNOW ABOUT THESE MEASUREMENTS? The variable that is the cause of change in the system is called the independent variable. The ramp s angle is the independent variable in this example. The variable that shows (or may show) the effect of those changes is called the dependent variable. The speed of the ball is the dependent variable. 4

5 Energy is a measure of a system s ability to change or create change in other systems. A car at the top of a ramp is able to move because it has energy due to its height on the ramp. The car s increase in speed as it moves is a change in the system that could not occur without energy. A stretched bowstring on a bent bow has energy, so it is able to create change in itself and in the arrow. Launching the car gives it energy due to its speed. Climbing the hill takes energy. The car climbs only so high because it only has so much energy. Making the car go faster gives it more energy and that is why it goes higher. This explanation is a model that links the height and speed through the idea of energy. 5

6 Distance and Time A measurement is a precise value that tells how much. Length is the meter Mass is the gram Volume is the liter 6

7 The second (sec) is the basic unit of time WRITE This diagram is a cross reference of time in Physics Who can explain what the relationship is in the pic? The graph shows that it takes the ball about 0.45 seconds to fall a distance of 1 meter. 7

8 HOW MUCH TIME IS THIS???? Seconds in a 1 minute Minutes in 1 hour Hours in 1 day Days in 1 year 1) 5 hours = minutes 2) 7 hours = minutes 3) 3 hours = minutes 6)120 minutes = hours 7)540 minutes = hours 8)780 minutes = hours 8

9 The graph to the right shows distance and time measurements taken during a long trip in a car. What information can we understand from the graph? Graph the following information: Future 7 Day Forecast Springfield MA TITLE 9/ / / / / / /

10 Nothing in the universe stays still. A book on a table appears to be sitting still, but Earth is moving in its orbit around the sun at a speed of 66,000 miles per hour. You and the book move with Earth. Speed is an important concept in physics and saying that something is fast is not descriptive enough to accurately convey its speed. A race car may be fast compared with other cars, but it is slow compared with a jet airplane. vs. Speed the rate at which position changes; the distance traveled divided by the time taken. 10

11 What can you tell me about the pictures? ] WHAT IS THE FASTEST THING IN THE UNIVERSE? = 8 minutes 150 million kilometers AWAY FROM EACH OTHER 11

12 Calculating speed Speed is calculated by dividing the distance traveled by the time taken. Symbol V D T Meaning FORMULA = V = D T Calculating speed 0 1 Distance (km) Time Take (h) kilometers 1.5 hours(h) 150 km 3. Speed = 100 km/h 12

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