***Quiz 6 retakes will be available at lunch today***
Signed up for College Center announcements?
Signing up for Schoology groups:
Sign in to Schoology
Go to the Groups tab at the top
Click “join group”
Enter the access code for your grade level
#Goals: SWBAT...
1. define free-fall without using the term, "force"
2. solve 1-D one stage and two stage kinematics problems using the UAM equations.
Warm-Up (4min)
Write a definition for free fall. Your definition cannot include the word force, and should include the word “touching”
An object in free-fall accelerates because of ____________
T/F an object must be moving downward to be in free-fall
The acceleration caused by gravity is 9.8m/s2 in the...
A. -x direction
B. -y direction
C. any direction
When solving free-fall problems, can you use any of the four UAM equations? If yes, which ones?
Why does Mr. P use the phrase, "the vacuum that you can breathe"?
CLASSWORK
1. #030A: Notes: Representing Free-Fall with Graphs
a. Draw a p-t graph. Draw a line representing the motion of an object that starts from position zero, and is in free-fall
b. hint: if you started from anywhere other than the origin, you'll want to revise your graph
hint: does the position change more in the first second, or in the second second?
c. revise if necessary
d. Draw a line in a new p-t graph representing the motion of an object in free-fall, that initially has a vertical velocity that's positive.
e. What would the slope be at the beginning of your graph, positive or negative? revise if necessary
f. Draw a v-t graph. Draw a line representing the motion of an object in free-fall.
g. hint: does the velocity change more in the first second, more in the second second, or is the velocity change constant?
2. #030B: Practice Problems w/ Free-Fall
- Solve 14 & 16 here: http://www.physicsclassroom.com/Class/1DKin/U1L6d.cfm
- Use GUESS
3. #028A (continued): Two-Stage Acceleration
Handout: (it's on Schoology "Two Stage Rocket")
Interactive Activity: LINK
At Home Learning (HW)
1. #028A: Two Stage Rocket is due electronically tonight by 11:59pm
2. #030C: Next class we will attempt more complicated Free Fall problems as we build towards our ramp/cup/ball bearing challenge
Take Notes: LINK 1
Watch the video, and answer the EdPuzzle Questions: LINK 2
#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
4. Describe the relationship between mass, net force, and acceleration
Warm-Up (4min)
I'm sick, so I won't be talking loud today. Keep your voices low.
Read the scenario below, then answer the questions at the end
You apply a force to the left to push a 89g matchbox car across the floor. Draw a free body diagram showing the scenario AFTER you release the car.
If asked to find the Force of Friction, would you need to do any unit conversions? Why/Why not?
CLASSWORK
1. #030A: The process of determining the value of the individual forces acting upon an object involve an application of Newton's second law (Fnet=m•a) and an application of the meaning of the net force. If mass (m) and acceleration (a) are known, then the net force (Fnet) can be determined by use of the equation.
Fnet = m • a
If the numerical value for the net force and the direction of the net force is known, then the value of all individual forces can be determined. Thus, the task involves using the above equations, the given information, and your understanding of net force to determine the value of individual forces.
To gain a feel for how this method is applied, try the following practice problems. The problems progress from easy to more difficult. Once you have solved a problem, click the button to check your answers.
Free-body diagrams for four situations are shown below. The net force is known for each situation. However, the magnitudes of a few of the individual forces are not known. Analyze each situation individually and determine the magnitude of the unknown forces.
A rightward force is applied to a 6-kg object to move it across a rough surface at constant velocity. The object encounters 15 N of frictional force. Use the diagram to determine the gravitational force, normal force, net force, and applied force. (Neglect air resistance.)
Practice #2
A rightward force is applied to a 10-kg object to move it across a rough surface at constant velocity. The coefficient of friction between the object and the surface is 0.2. Use the diagram to determine the gravitational force, normal force, applied force, frictional force, and net force. (Neglect air resistance.)
A rightward force is applied to a 5-kg object to move it across a rough surface with a rightward acceleration of 2 m/s/s. The coefficient of friction between the object and the surface is 0.1. Use the diagram to determine the gravitational force, normal force, applied force, frictional force, and net force. (Neglect air resistance.)
A rightward force of 25 N is applied to a 4-kg object to move it across a rough surface with a rightward acceleration of 2.5 m/s/s. Use the diagram to determine the gravitational force, normal force, frictional force, net force, and the coefficient of friction between the object and the surface. (Neglect air resistance.)
At Home Learning (HW)
1. Complete the problems from 30A. Need help? The answers to all five practice problems are here: http://www.physicsclassroom.com/class/newtlaws/Lesson-3/Finding-Individual-Forces
NGSS Standard (this is what we're learning with this unit)
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.]