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Types of Motion - How do linear, projectile, circular, and rotational motion differ?
Types of Motion - How do linear, projectile, circular, and rotational motion differ?
Linear Motion
Linear Motion
So far in Physics, we have been studying and calculating both horizontal and vertical LINEAR motion. In linear motion, all motion (velocity), acceleration, and force vectors are in the same horizontal or vertical plane. In this type of motion, we learned:
Net force and acceleration always go the same direction.
If acceleration and velocity are the same direction, the object is speeding up. If acceleration and velocity are opposite directions, the object is slowing down.
Projectile Motion
Projectile Motion
Projectile motion is also known as 2-dimensional (because it has vertical and horizontal components), curvilinear (because it looks like linear motion that has been curved), or ballistic (anything "shot") motion. Bullets fired from a gun, basketball free throws, and baseball pitches are all this type of motion. It's important to remember:
The velocity vector will change direction, but force and acceleration always point toward the ground.
Horizontal and vertical motions are always calculated SEPARATELY. Horizontal acceleration is always 0m/s/s and vertical acceleration is always 9.8m/s/s.
Circular Motion
Circular Motion
Circular motion happens when force and acceleration always remain perpendicular to the velocity vector of the object. This causes the object to assume a circular path. Satellites moving around the earth are an example of circular motion. It's important to remember:
The velocity, force, and acceleration vectors are always changing direction in circular motion - the force and acceleration vectors are always perpendicular to the velocity vector.
The force and acceleration vectors always point to the center of the circle. This is know as "centripetal" or center-seeking force and acceleration.
Rotational Motion
Rotational Motion
Rotational motion occurs when entire objects rotate about a fixed axis. Tires rotating on a car are probably the most typical rotational motion known. With rotational motion, it's important to remember:
Velocity, force, and acceleration vectors are CURVED.
There is an entirely different set of formulas for rotational motion.
RADIANS!!
RADIANS!!
Angles in ROTATIONAL MOTION are calculated in radians rather than degrees. Linear, projectile, and circular motions tend to be calculated in degrees.
Below is an interesting article explaining the benefits of using radians as compared to degrees:
Theme Park Ride Physics
Theme Park Ride Physics
Intro Lab - Gauntlet Timing of Rolling Objects
Intro Lab - Gauntlet Timing of Rolling Objects
This lab allows students to investigate variations in the rotational motion of objects rolling down a ramp. We do not get into the formulas behind this, but we do discuss the role of "moment of inertia".
The movie clip shown is from "Quigley Down Under". This is a long-distance rifle shot scene at the beginning of the movie.
Skeptical Questions In Science
Skeptical Questions In Science
The skeptical question topic for this unit involves projectile motion in terms of a long-distance rifle shot. Skeptical questions are thoughtful "Why-based" questions which address biases in scientific material. This type of question is not seeking scientific facts.
The article associated with this unit is listed below:
Projectile Motion Bullet Graphs
Projectile Motion Bullet Graphs
One of the most documented versions of projectile motion involves ballistics - the study of the motion of bullets. This field of study involves well defined parameters and test data for hundreds of bullets according to rise and drop, distance traveled, and accuracy.
BallisticsTrajectoryChart.pdfFor this activity, students use the above information to enter data sets into Logger Pro for ten different bullet types. These data sets include bullet rise and fall at 100yds, 200yds, MRT (Mid-Range Trajectory) and MPBR (Maximum Point Blank Range). Logger Pro is then used to plot relative bullet trajectory or path differences.
This is where the first 80% Quiz would typically occur for the unit. Since Unit 4 is relatively short, there will only be one 80% Quiz at the end of the unit.
This is where the first 80% Quiz would typically occur for the unit. Since Unit 4 is relatively short, there will only be one 80% Quiz at the end of the unit.
2D Motion Formulas - Type 1
2D Motion Formulas - Type 1
For Type 1 motion, there is no initial launch angle. Because of this, there is no initial vertical velocity.
For this formula set, g = (+)9.8m/s/s
"u" = initial horizontal velocity
"x" = horizontal distance
"h" = vertical distance
2D Motion Formulas - Type 2
2D Motion Formulas - Type 2
For Type 2 motion, there is an initial launch angle. Because of this, there are initial vertical and horizontal velocities.
For this formula set, g = (+)9.8m/s/s.
"u" is initial velocity along the curve of motion
"x" is horizontal distance
These are the Type 1 and 2 formula notes we go through in class. The variables differ somewhat from the formulas shown above.
2D Projectile Motion Formula Notes.pdf
Logger Pro Video Features
Logger Pro Video Features
One of the most useful features of Logger Pro is being able to analyze the motion parameters in a video. This allows us to determine the position, velocity, acceleration, and time associated with common motions.
The following secondary lab allows you to use this feature with an event of your choice.
Logger Pro Video Analysis Lab
Logger Pro Video Analysis Lab
The purpose of the secondary unit lab is to (1) learn to use the video analysis feature on Logger Pro, and (2) analyze a daily motion with the video feature
Questions:
What is the class estimate of the acceleration of gravity based on a video analysis of a dropped object?
What is the range of accelerations and forces for the class events analyzed with the video feature on Logger Pro?
"If-Then-Due-To" Hypothesis: "If Logger Pro is used to analyze a motion video, then accelerations should be able to be determined due to Logger Pro's ability to create PVAT graphs."
Variables: (x) Time; (y) Position
Controls: Gravity = 9.8m/s/s; internal class comparison control
Constants: same video device, same meter stick standard, same use of VT graph slope as the best estimate of acceleration, same use of F=ma to determine force
Logger Pro Commands.pdfREMINDER: Be sure to include a screenshot of both the object drop PVAT graphs and the second motion PVAT graphs in your data section. Both these graph sets should have the slope of the VT graph clearly labeled!
The spreadsheet shown to the left can be used for internal comparison class data.
Full Lab - Video Analysis of a Basket Ball Free Throw
Full Lab - Video Analysis of a Basket Ball Free Throw
The purpose of this lab is to use the Logger Pro video analysis feature to determine differences in the basketball free throws of physics students
Questions:
What patterns occur in the horizontal and vertical accelerations of basketball free throws?
What factors might affect the accelerations of this event?
Do differences in athletic skills affect free throw accelerations?
"If-Then-Due-To" Hypothesis: "If a student's basketball free throw is plotted using Logger Pro's video feature, then specific differences can be determined based on kinematic graph differences."
Variables: (x) time; (y) position
Constant: basketball free throw distance, hoop height, ball size
Control: x-acceleration = 0m/s/s; y-acceleration = (-)9.8m/s/s
"Learning-2-Learn" and Retrieval Assignments (Required before taking the unit test!) and Unit Calibration Test
"Learning-2-Learn" and Retrieval Assignments (Required before taking the unit test!) and Unit Calibration Test
Bullet Graph Intro "Lab"
Practice (2D Motion Problem Set)
NO 80% Quiz #1
80% Quiz 2
Reflections on the back of Quiz 2
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