#Goals: SWBAT...
1. define inertia
2. list contact & non-contact forces
3, Answer inertia related questions
Warm-Up (5min)
Copy and fill in the correct answers for the following:
1. Blood rushes from your ______ to your ____ while quickly stopping when riding on a descending elevator.
2. To dislodge ketchup from the bottom of a ketchup bottle, it is often turned ______ down and thrusted downward at high speeds and then abruptly ______.
3. Headrests are placed in cars to prevent whiplash injuries during _________ collisions.
4. While riding a skateboard (or wagon or bicycle), you fly _______ off the board when hitting a curb or rock or other object that abruptly halts the motion of the skateboard.
CLASSWORK
1. #036A: HW Review:
Define "Force" LINK
Make two lists, one with examples of contact forces, and one with non-contact (field) forces
What is unique about field forces?
Inertia: The tendency of an object to resist a change in state of motion. A “change in state of motion” means a change in an object’s velocity. a = Δv/Δt , therefore inertia can also be defined as: The tendency of an object to resist acceleration.
2. #036B: Water Demo of Inertia
What is in the plates? Do the plates have tall sides?
We'll have a race, from the sink, to the fire extinguisher, to the projector screen, and back to the sink. If you spill twice, you lose. If you aren't first, you lose.
GO WIN.
Q1: Why is it hard to keep the water in the plate?
Q2: What physics concept does this illustrate?
3. #036C: read the following: http://www.physicsclassroom.com/class/newtlaws/Lesson-1/Inertia-and-Mass While you're reading, think about how mass and balanced/unbalanced forces affect an object's motion, and answer the following:
a. Who was the first well known scientist to develop the concept of inertia?
b. Sketch and describe the scenarios of inclined planes (there are 3, all black ramps, with grey spheres on them), how do skateboarders and snowboarders use the concept of inertia to their advantage?
c. During the Winter Olympics there was an event which used these curved "inertial planes" to allow riders to do spectacular aerial tricks. What was the event?
d. How does an object's own mass affect its motion?
e. What type of motion is caused by unbalanced forces?
4. 037B: Inertia Practice Questions
***want to get a jump on tomorrow and have time to work on your lab in class? Do these five problems today***
LINK Answer 1, 3, 4, 5, 6
we will review these Tuesday
At Home Learning (HW)
1. Complete any unfinished classwork
2. #036D: Inertia & Newton's 1st Law
Take Notes: LINK 1
Watch the video, and answer the EdPuzzle Questions: LINK 2
3. Review for Tuesday's quiz.
Begin solving by doing G, U, and E from GUESS. Keep in mind that since this is a 2-dimensional problem, you'll need to separate your given/unknown/equation in an x-part and a y-part:
You accidentally throw your car keys horizontally at 8.0m/s from a cliff 64m high. how far from the base of the cliff should you look for your keys?
X-Information Y-Information
G
U
E
S
S
ANSWER: https://youtu.be/zo3t-IAY2Oo
4. Lab #3: Ball in a Cup is due electronically Thursday 11:59pm
5. Notes/CW/HW check for this week's assignments, due Friday
- be organized. Each day should follow this format:
DAY XX
Warm-Up
- whatever it is
Classwork
- 36A
- 36B
- etc
Homework
- notes
- edpuzzle answers
Goals: SWBAT...
1. solve a time problem using the free-fall equation
2. Collect all lab data
Warm-up
1. Find/write the free-fall equation for free-fall time of an object with initial velocity zero
2. Find the free-fall time for an object with initial velocity zero and initial height of 3m
036A: LAB DAY - Lab Data Collection
Collect all your lab data today
Sample Procedure
This is one set of steps you can use to successfully complete the lab.
Make a data table with displacement, time, and speed. On your actual table (the one made of wood), mark your xi and xf points with small pieces of tape - I suggest that your displacement length should be .20m - .40m, but it's up to you. You must collect constant velocity data on a FLAT SURFACE. Collect ~5-10 trials for the time. Take the average of those ten time values to find your average time. You may want to video
Use the time and displacement to find vx (x-velocity).
Measure Δy between the top of the cup (the cup and the table top (you can measure the ycup, ytabletop, and _________ the two.
solve the free-fall problem to determine the time to fall Δy
Use the free-fall time and the vx you calculated to calculate Δx for your projectile motion
Use a plumb bob to find the initial x position for your projectile motion
measure out the location for your cup. Mark it with a piece of tape
When you're ready, call me over for your one attempt, and put the cup in the correct spot. Video your attempt.
036B: Learning at Home (HW):
1. Solve the free-fall problem for the time it will take your ball-bearing to fall from the table to the floor
#Goals: SWBAT...
1. Describe which friction coefficient refers to moving objects, and which refers to objects at rest
2. Draw accurate FBD's
3. Solve problems involving kinetic and static friction AND ACCELERATION
Warm-Up (5min)
Copy the following, then draw the FBD and list all the given and unknown information.
1. At a wedding reception, you notice a small boy who looks like his mass is about 25 kg running part way across the dance floor, then sliding on his knees until he stops. If the kinetic coefficient of friction between the boy’s pants and the floor is 0.15, what is the frictional force acting on him as he slides?
CLASSWORK
1. #036A: An Example of how to solve a Friction Problem, plus some Practice Problems
A. We will solve the warm-up problem together, then you'll solve a few problems on your own
Take notes as we solve
B. Solve these on your own:
Theory Question:
2. Ryan is moving to a new apartment and puts a dresser in the back of his pickup truck. When the truck accelerates forward, what force accelerates the dresser? Under what circumstances could the dresser slide? In which direction?
Math Questions:
3. You apply a 98N force on a 25kg wood box sliding across a wood floor. What is the resulting acceleration?
FYI: for wood on wood, µs = 0.50 and µk = 0.20 ANSWER: 2.0m/s2
4. You help your mom move a 41-kg bookcase to a different place in the living room. If you push with a force of 65 N and the bookcase accelerates at 0.12 m/s2, what is the coefficient of kinetic friction between the bookcase and the carpet? ANSWER: µk=.15
5. Shuffleboard is like curling, but for old people. A shuffleboard disk is accelerated to a speed of 5.8 m/s and released. If the coefficient of kinetic friction between the disk and the concrete court is 0.31, how far does the disk go before it comes to a stop? The courts are 15.8 m long. ANSWER: 5.5m
At Home Learning (HW)
1. Complete the problems from #036A
2. #036B: Watch/take notes/complete edPuzzle on the following:
A. (2:57) Everybody Brought Mass to the Party! - EDpuzzle
B. (7:10) Introduction to Work with Examples - EDpuzzle