Kinematics – Kinematic Equations

http://www.aplusphysics.com/courses/honors/kinematics/honors_kinematics.html

Unit #2 Kinematics

Objectives and Learning Targets

Use kinematic equations to solve problems for objects moving at a constant acceleration in a straight line and in free fall.

Resolve a vector into perpendicular components: both graphically and algebraically.

Unit #2 Kinematics

Kinematic Equations These equations can help you solve for key variables

describing the motion of an object when you have a constant acceleration. Once you know the value of any three variables, you can use the kinematic equations to solve for the other two!

Unit #2 Kinematics

Key Kinematics Variables

Variable Meaningv0 Initial velocityv Final velocityΔx Displacementa Accelerationt Time elapsed

Problem Solving Strategy In using these equations to solve motion problems, it’s important to take care in

setting up your analysis before diving in to a solution. Key steps to solving kinematics problems include:

1. Labeling your analysis for horizontal (x-axis) or vertical (y-axis) motion.

2. Choosing and indicating a positive direction (typically the direction of initial motion).

3. Creating a motion analysis table (v0, v, Δx, a, t). Note that Δx is a change in position, or displacement, and can be re-written as x-x0.

4. Using what you know about the problem to fill in your “givens” in the table.

5. Once you know three items in the table, use kinematic equations to solve for any unknowns.

6. Verify that your solution makes sense.

(Note: these equations work for vertical and horizontal motion)Unit #2 Kinematics

Sample Problem #1 – Horizontal Motion

Unit #2 Kinematics

Sample Problem #1 – Horizontal Motion

Unit #2 Kinematics

Sample Problem #2 – Vertical Motion

Unit #2 Kinematics

Sample Problem #2 – Vertical Motion

Unit #2 Kinematics

Sample Problem #3 – 2 Stepper

Unit #2 Kinematics

Sample Problem #3 – 2 Stepper

Unit #2 Kinematics

Sample Problem #4

Unit #2 Kinematics

Question: An astronaut drops a hammer from 2.0 meters above the surface of the Moon. If the acceleration due to gravity on the Moon is 1.62 meters per second2, how long will it take for the hammer to fall to the Moon’s surface?

Answer:

Create Your Own Problem Create your own Horizontal Motion Kinematics

Problem and solve it. Feel free to make it funny, but keep it clean.

Create a second problem making it vertical. Solve it also.

Trade with a neighbor and solve each other’s problems before turning them in.

Unit #2 Kinematics