1 Honors Physics Exam 1 Review

2 Units A measurement always has a unit. QuantityUnit NameUnit Symbol LengthMeterm TimeSeconds Masskilogramkg Some SI standard base units

3 Conversion Factors 2 mile/hr = __ m/s

4 Precision and Accuracy Accepted (true) value is 1.00 m. Measurement #1 is 0.99 m, and Measurement #2 is m. – ____ is more accurate: #1 #2 closer to true value – ____ is more precise:uncertainty of m (compared to 0.01 m)

5 Significant Figures (Digits) 1. Nonzero digits are always significant. 2. The final zero is significant when there is a decimal point. 3. Zeros between two other significant digits are always significant. 4. Zeros used solely for spacing the decimal point are not significant.

6 When manipulating measurements The sum or difference of two measurements is only as precise as the least precise one. The number of significant digits in a product or quotient is the number in the measurement with the least number of significant digits

7 Position Position: Location, where an object is  Frame of Reference  Direction: always define positive direction  Reference point: where d = 0?

8 Displacement  d = d f - d i – Magnitude: how far – Direction: Negative sign indicates direction only, it has nothing to do with magnitude. Displacement has nothing to do with the actual path. It depends only on the initial and final positions.

9 Distance (D) Total distance is not necessarily equal to the magnitude of total displacement.

10 Average Velocity

11 Average speed

12 Constant Velocity

13 Problem Solving Strategy Set up Frame of Reference Write down given and unknown Write down useful equation Manipulation equation to express unknown as a function of other givens Plug in numbers and get result Answer question in physical terms if needed

14 velocity Tangent line d t titi tftf = average velocity from time t i to t f Slope of tangent line = instantaneous velocity at time t i

15 Displacement from v-t graph v t titi tftf Displace = Area under curve

16 Instantaneous Speed Instantaneous speed is magnitude of instantaneous velocity. Average speed is not necessarily equal to magnitude of average velocity.

17 Average Acceleration

18 Instantaneous Acceleration Instantaneous acceleration is average acceleration when the time interval becomes very, very small. On a velocity-time graph, the instantaneous acceleration at any time is given by the slope of the line tangent to the curve at that time.

19 Constant acceleration motion a = constant. Also, let t i = 0:

20 Free-Fall Motion Assume no air resistance. (Valid when speed is not too fast.) a = g, downward (g = 9.81 m/s 2 )  Acceleration can be positive or negative, depending on what we define as the positive direction.  g is always a positive number, equivalent to 9.81 m/s 2.  Does not matter if the object is on its way up, on its way down, or at the very top.  g is acceleration due to gravity (It is not gravity.) g does not depend on mass of object.