2. Kinematics 1-D Motion

3. Scalar A SCALAR is ANY quantity in physics that has MAGNITUDE, but NOT a direction associated with it. Magnitude – A numerical value with units. Scalar Example Magnitude Speed20 m/s Distance10 m Age15 years Heat1000 calories

4. Vector A VECTOR is ANY quantity in physics that has BOTH MAGNITUDE and DIRECTION. VectorMagnitude & Direction Velocity20 m/s, N Acceleration10 m/s/s, E Force5 N, West Vectors are typically illustrated by drawing an ARROW above the symbol. The arrow is used to convey direction and magnitude.

5. Defining the important variables Kinematics is a way of describing the motion of objects without describing the causes. You can describe an object’s motion: No matter HOW we describe the motion, there are several KEY VARIABLES that we use. SymbolVariableUnits tTimes aAccelerationm/s/s or m/s 2 d or x or yDisplacementm vivi Initial velocitym/s vfvf Final velocitym/s g or a g Acceleration due to gravity m/s/s or m/s 2

6.  Here are the 5 kinematic equations. We will be using them often - memorize them. Kinematics: Description of motion Kinematic Equations d = v av t v f = v i + at d = v i t + ½ at 2 v f 2 = v i 2 + 2ad displacement eq'n average velocity eq'n position eq'n velocity eq'n timeless eq'n  We'll even give them names: v av = v f + v i 2

7. Kinematics: Description of motion 2-4 Kinematic Equations v f = v i + at d = v i t + ½ at 2 v f 2 = v i 2 + 2ad

8. Kinematics: Description of motion 2-4 Kinematic Equations (1) How far will Pinky and the Brain have gone in 30.0 seconds if their acceleration is 20.0 m/s 2 ? A good way to solve these problems is to list the things you know, and the thing you want: a = 20 m/s 2 KNOWN (Given) v i = 0 m/s(Implicit) t = 30 s (Given) WANTED d = ? FORMULAS v f = v i + at v f 2 = v i 2 + 2ad  Since t is known, eliminate the timeless eq'n:  Since v is not wanted, eliminate the velocity eq'n: SOLUTION d = v i t + ½ at 2 d = 0(30) + ½ ( 20)(30) 2 d = 9000 m d = v i t + ½ at 2

9. Kinematics: Description of motion 2-4 Kinematic Equations (2) How fast will Pinky and the Brain be going at this instant? a = 20 m/s 2 KNOWN (Given) v i = 0 m/s(Implicit) t = 30 s (Given) WANTED v f = ? FORMULAS v f = v i + at d = v i t + ½ at 2 v f 2 = v i 2 + 2ad  Since t is known, eliminate the timeless eq'n:  Since d is not wanted, eliminate the position eq'n: SOLUTION v f = v i + at v f = 0 + 20(30) v f = 600 m/s

10. Kinematics: Description of motion 2-4 Kinematic Equations (3) How fast will Pinky and the Brain be going when they have traveled a total of 18000 m? a = 20 m/s 2 KNOWN (Given) v i = 0 m/s(Implicit) d = 18000 m (Given) WANTED v f = ? FORMULAS v f = v i + at d = v i t + ½ at 2 v f 2 = v i 2 + 2ad  Since t is not known, eliminate the position and the velocity eq'n: SOLUTION v f 2 = v i 2 + 2ad v f 2 = 0 2 + 2(20)(18000) v f 2 = 720000 v f = 720000 v f = 849 m/s