DAY 27
#Goals: SWBAT...
1. solve 1-D kinematics problems using the UAM equations.
2. Solve problems where there are two separate stages (or rates) of acceleration
WARM-UP
A bike accelerates uniformly from rest to a speed of 7.10 m/s over a distance of 35.4 m. Determine the acceleration of the bike.
Use GUESS
CLASSWORK
1. #027A Practice!
Lets try a few more UAM problems. Keep increasing your skill level :)
Complete 8-11 here ---> - LINK - The Physics Classroom
Use GUESS
2. #027B: UAM Problems with Multiple Stages
Toy Car UAM Problem with Two Different Accelerations
Tuesday, you'll solve a problem similar to the one below, and to do so, you'll need to understand what happens during multiple stage acceleration.
"A two-stage rocket accelerates from rest at +4.00 m/s/s for 10.0 seconds. It then accelerates at +3.00 m/s/s for another 7.00 seconds. After the second stage, it enters into a state of free fall. Determine the maximum speed"
Table of Contents/Agenda:
0:26 Reading the problem
0:46 Seeing the problem
1:11 Translating from words to physics
1:58 Splitting the problem into two parts
3:13 Fixing the knowns (common mistakes)
4:35 How do we know we can use the UAM equations?
5:19 Drawing a picture to better understand the problem
6:00 Finding the missing known
7:29 What are we finding again?
8:45 The end of part 1 is the start of part 2!
9:29 Beginning to solve the problem :)
11:19 Solving part (b)
13:53 What is wrong with solving the whole thing at once?
16:03 Rapping it up!
At Home Learning (HW)
1. Watch the video on multiple-stage acceleration: (LINK), take notes (LINK), and answer the EdPuzzle questions
2. Complete any remaining practice problems from Day 25-27
3. Quiz on Acceleration covering Days 25-27 on Wednesday October 2nd
#Goals: SWBAT...
1. Draw correct FBD's, with appropriate vector magnitude and direction.
2. Support classmates with helpful tutoring
3. Use FBD's to find Net Force
Warm-Up (4min)
Copy and fill in (or choose) the correct answers for the following:
1. What is the equation which represents Newton's 2nd Law of Motion?
2. What mathematical operation does Σ represent?
3. What are the units of a Newton?
4. Draw a free body diagram representing a book, sliding on a horizontal table, with applied force of +10.0N, and friction of -4.5N.
CLASSWORK
1. #026C (continued): Modeling and Practice
We're going to continue to help each other. From yesterday, here's our list of best tutoring practices:
Don't give student the answer
let student think on their own
ask guiding questions
guide student to figure out mistakes
be nice, calm, patient, supportive
try to make student solve problem
review the topic (this is a great way to guide students thru finding their mistake)
give a person a fish vs. teach a person to fish
Practice Problems
A book is at rest on a tabletop. Diagram the forces acting on the book.
A gymnast holding onto a bar, is suspended motionless in mid-air. The bar is supported by two ropes that attach to the ceiling. Diagram the forces acting on the combination of gymnast and bar.
An egg is free-falling from a nest in a tree. Neglect air resistance. Diagram the forces acting on the egg as it is falling.
A flying squirrel is gliding straight down (no flapping of the wings) from a tree to the ground at constant velocity. Consider air resistance. Diagram the forces acting on the squirrel.
A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.
A rightward force is applied to a book in order to move it across a desk at constant velocity. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.
A college student rests a backpack upon his shoulder. The pack is suspended motionless by one strap from one shoulder. Diagram the vertical forces acting on the backpack.
A skydiver is descending with a constant velocity. Consider air resistance. Diagram the forces acting upon the skydiver.
<Happy Valentines Day - complete the three problems below>
A force is applied to the right to drag a sled across loosely packed snow with a rightward acceleration. Neglect air resistance. Diagram the forces acting upon the sled.
A football is moving upwards towards its peak after having been booted by the punter. Neglect air resistance. Diagram the forces acting upon the football as it rises upward towards its peak.
A car is coasting to the right and slowing down. Neglect air resistance. Diagram the forces acting upon the car
#027A: Determining the Net Force
Notes:
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
If either all the vertical forces (up and down) do not cancel each other and/or all horizontal forces do not cancel each other, then an unbalanced force exists.
Review the following. Are the forces balanced?
If the forces are unbalanced, a NET FORCE exists
What is the net force in each of the above?
So what? Well, a net force causes acceleration, and we can use that fact to solve problems.
#027B: A Net Force Causes Acceleration - Practice Problems
Navigate to: http://www.physicsclassroom.com/class/newtlaws/Lesson-2/Determining-the-Net-Force
Scroll halfway down the page to "A Net Force Causes Acceleration "
Looking at the Descriptions of Motion, what is the net force for each scenario? (answers can be positive, negative, or zero)
Try the two Check for Understanding problems on your own for practice. Get peer help if needed.
At Home Learning (HW)
1. Complete Lab #2 due Thursday
This should include the following. Topics in CAPS are especially important.
Names & Group Member Names
Purpose
Materials
PROCEDURE
this should be specific/detailed enough that another person could read them, and do the lab correctly.
DATA
time data from finding Δx
SAMPLE CALCULATIONS
show how you did all the math leading up to, and including, solving Δx=vixΔt
RESULTS
what happened?
ANALYSIS
- Any errors? If so, which ones, and how did they affect your results?
- If you didn't have any errors, why not? What steps did you take that made your lab work so well?
Conclusion
- Sum up the lab, the experience, how did it go?
If you'd like to use the template and see the rubric, here they are again
Grading Rubric LINK
Lab Template: LINK
2. #027C: Your homework, due Thursday, is to prepare for class by watching 8.5 minutes worth of video. You should understand how to solve net force problems after watching the video
Take Notes: Introductory Newton's 2nd Law Example Problem
Watch the video, and answer the EdPuzzle Questions: EDpuzzle
NGSS Standard
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship amongthe net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could 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 sliding 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.]