How is the syllabus helpful? @glasshours I don’t find it helpful, except saying you will be tested on these topics…
@tealpanda - pages 24-102 of the PDF
1 is actually directly explained in the course description :P Basically, you want to change the object's direction of motion and decrease its kinetic energy. Perpendicular forces (including perpendicular components of forces) to the line of motion change the direction of motion; you can eliminate B right away, because there is no perpendicular force. Kinetic energy is decreased when there's a force vector pointing opposite to the velocity vector; the force in A has no x component, the x component of the force in C points the same direction as the velocity vector, increasing the kinetic energy, so you're left with D.
@Mathman97 So basically with one closed end tube to calculate frequency use f=nv/4l n is number of harmonics, v is given velocity (usually) and l is length of pipe. Wavelength in same type of tube is 4l/n
for an open ended tube on both ends to get frequency you use nv/2l and to get wavelength you use 2l/n. same symbols denote same meanings
“use f=nv/4l n is number.” Btw there should have been a period after the equation f=nv/4l.
STANDING WAVES: n= antinodes n+1=nodes
λ(n)=2L/n
f(n)=nv/2L
OPEN END PIPES:
n= nodes n+1=antinodes
λ(n)=2L/n
f(n)=nv/2L
CLOSE END PIPES:
antinodes/nodes= n+1/2
λ=4L/n
f(n)=nv/4L
@glasshours How far did you read up to on that pdf of description?
How do you do the density problem with the planets?
For a closed pipe use the formula and use odd numbers :1,3 and for an open pipe use even:2,4
i think
@Mathman97 - Tbh, I don’t really understand how people use equations to solve pipe problems; it’s much easier just using logic imo. At open ends, you have antinodes, and at closed ends, you have nodes. Nodes are points that don’t displace (i.e. if you think of a sine function, where the x is 0); antinodes are at the crests and troughs.
Fundamental frequency is the lowest frequency that can exist in the pipe, so basically just connecting the two ends. If you have an open pipe, you’re connecting two antinodes, so the length of the pipe is is half the wavelength, etc.
Can someone go over #13 on the practice exam? Thanks!
@yoda4ever Think about torque and where the center of mass would be located.
The center of mass would be closer to the person, so when the person moves right, the center of mass must not change location. So when the kid goes right, the raft shifts left to balance out the weight of the person.
All the pictures line up, just draw a line from the center of mass on the top picture down, and you’ll see © gives appropriate center of mass.
I feel like there’s a big emphasis on center of mass. idk,.
ikr
@googlingtony Only teachers have the questions
@CeLcel wait did you remove the link?
@KE3299 no, everything got removed though. Google docs aren’t allowed, sorry.
No, I did. Links to Google Docs are not allowed
@CeLcel Thanks!
- resistors in series all have the same current, while in parallel, total current into a junction equals that coming out.
- Density equals mass divided by volume and is used to find the mass of another planet usually.
For the practice exam, what are the answers to 5 and 6 and why?
@skieurope am I allowed to post the answers?