You should know the following for the Unit 4 Test:

• Speed = Distance ÷ Time and when we graph speed, distance is on the y-axis and time is on the x-axis...........Constant speed on a graph is a straight line.

• Acceleration = Speed ÷ Time.........Constant acceleration is a straight line on a speed vs. time graph
• Look at these Sample Graphs to see the difference:
  

• Velocity is speed plus the given direction of an object.

• Friction is when two surfaces rub against each other. Friction causes things to slow down, heat up, and wear out.

• Forces are pushes or pulls. They can add together (if they’re going the same direction) or subtract from each other (if they are acting in opposite directions). If they add together they generally form unbalanced forces. If they cancel each other out they form balanced forces.

• Unbalanced forces cause objects to change their motion. Like:

Speed up….Slow down….Start moving….Stop moving...Change Direction

• More mass, more inertia. Inertia is the tendency of an object to remain in motion or stay at rest.

• In order to test an idea you would:

Make a hypothesis: “IF I do _______________ , THEN I think _______________ will happen.”
Test the hypothesis: “I will change ____________ and record what happens. I will repeat it several times.
Analyze the data: “I wrote down my observations in this chart and then made a graph.”
Make conclusions based on facts: “When I did _______ the measurement changed to ________, this proves/disproves my hypothesis as correct.”