ICP TCHS “Motion”

Students who demonstrate understanding can: HS- PS2-1. Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data will include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]

What is motion? u motion - a constant change in position u distance - the result of motion in any direction u displacement - the result of motion in a particular direction(sign indicates direction) u scalar - a quantity having magnitude only u vector - a quantity having magnitude and direction

Speed or Velocity? u speed - the time rate of change in distance u velocity - the time rate of change in displacement u Speed is a scalar. Why? u Velocity is a vector. Why? u For now, we will use the terms speed and velocity without regard to direction.

Sample Problem u Suppose you drive 30 miles in 0.5 hours. What is your average speed in mi/hr? ft/s? u How did you estimate your answer to the first part of the question? u How can you calculate the answer to the second part of the question? u Page 72, Practice Problems 1,2 in notes

Acceleration u acceleration - the time rate of change in velocity u a = (v f - v i ) / t u A car moving at 25m/s increases to 55m/s in 5 seconds. Find its rate of acceleration. u a = (55m/s - 25m/s)/5s = (30m/s)/5s = 6m/s 2 u What does negative acceleration indicate?

Experiment u You will roll a ball down an incline and measure the time required for it to roll 0-10cm, 0-20cm, etc up to 0-100cm. Make three trials and average each. u Record all average values in a data table. u Plot a graph of x vs t. u Analyze the graphs with regards to constant and varying slopes. u Write a report for this experiment.

2-3 Falling Objects u When gravity acts on an object, the object is accelerated at the rate of 9.8m/s 2, 980cm/s 2, or 32ft/s 2. These numbers are constant and should be memorized. Any time free fall is involved, a in an equation should be replaced with g, the acceleration due to gravity. u Page 80, 1-7

Lab Report Format 40 pts-due next class meeting after lab is completed u Upon completion of each experiment, you will turn in a lab report using the following format. The report will be referred to as a ppoc. u p - Purpose - usually one statement u p - Procedure - steps which will duplicate what you have done, you may use diagrams u o - Observation - includes data (use data table when possible) and calculations u c - Conclusion - what you learned, possible reasons for error, suggestions for improvement and opinion

Experiment u You will roll a golf ball down an incline and measure the time required for it to roll 0-10cm, 0- 20cm, etc up to 0-100cm. Make three trials and average each. u Record all average values in a data table. u Plot a graph of x vs t. Plot a graph of  v vs t. u Analyze the graphs with regards to constant and varying slopes. u Write a lab report for this experiment.

Plotting Graphs u 1. Identify the independent and dependent variables. u 2. Choose the appropriate range and plot the independent variable values on the x-axis and dependent on the y-axis. u 3. Decide if the origin is an appropriate point. u 4. Number and label the horizontal axis. u 5. Repeat steps 2-4 for the dependent variable. u 6. After plotting all points, draw the best fitting line through as many points as possible. u 7. Give the graph a title that best describes what it represents.

Content Terms Vocabulary u motion u distance u displacement u speed u velocity u acceleration u scalar u vector