Learn Physics – Mr. Trampleasure
Resources for high school physics students and teachers
We added energy equations and the work work/energy theorem to our energy knowledge. In physics, work is used to add or remove energy from a system.
Class/homework: Page 151, # 9-18
We worked on an energy simulation using the PhET Energy Skate Park simulation. You can see the assignment here, and the simulation here:
We started learning about power. Textbook Section 5.6, pages are 142-146. Solve problems 48-54 on page 154.
Here are the slides from Wednesday and Thursday
Solution for Problem 14:
Click here to see the videosSlideshow below, or a PDF below that.
Homework, Monday, January 6th. Problems 1-4 and 7-8.
Draw a sketch of each problem before you start it!
Solve some in class today, finish the rest for homework.
If you have any questions as you review or the final, please post them here.
Posting guidelines
Today you will use a force sensor and a stopper on a string to determine the relationship between the speed of the stopper and the force required to keep it in a circle.
We have mostly discussed forces as changing the magnitude of the velocity of an object. In this unit, we will examine and quantify the relationship between forces and a change in direction. The relationship between force, mass, and acceleration has been modeled mathematically as:
a = Fnet/m
When the value of the velocity is changing, we can easily re-write this as
vf – fi = Fnet/m
But iif the magnitude of the velocity is constant–for example running around the circle end of the track at a constant speed–we need another way to calculate the acceleration
Keep in mind, that the units of acceleration are m/s/s, so whatever formula we develop should have those same units.
We can predict that, as an object changes direction, the mass will still affect the amount of force needed to accelerate it (remember, in this case we are only looking at the change in direction and its affect on acceleration).
With your group, brainstorm a couple of variables that might affect the amount of force needed to change the direction of an object. Picture yourself in a car going around curves; what would affect the force you experience.
In this course, we will generally model objects moving in circles, not parabola or other shapes without a constant radius.
For each variable you select, use your past experiences and your knowledge of forces to predict if increasing that variable will increase or decrease the amount of force necessary to keep it in a cicle.
Write an equivelance statement for a in terms of your variables. Keep in mind your units to see if they combine for m/s/s.
Now it’s time to test our your prediction.
We will finish our study of forces the week of 11/18-21, and take the unit test on Thursday the 21st.
Friday we will start on circular motion: Forces that change direction not speed.
Today we will work on the 2019 released FRQ Problem 2.
You can find the released problem and problem grading rubric here. We are working on Problem 2 (image above) which focuses on forces.
To prepare for next week’s test, be sure to review the video tutorials here.
If you don’t have a scientific calculator by the test next week, I will be happy to provide you with a table of trigonometric identities and teach you how to use it (I guess I’m a dinosaur–this is how I learned to do SOHCAHTOA, and we didn’t call it that).
The videos today are all from Flipping Physics.
Remember that as you watch these videos, when a problem/question is presented, try writing out the answer before you continue with the video–then check yourself as you progress through the video.