Physics 11-13-18 A Look Back at Chapter 4 Concepts

PHYSICS: Leaves gracefully falling – can you apply concepts from this chapter to explain? Practice, practice practice the problems, but don’t forget the conceptual stuff! Here’s our short look at some additional concepts.

How do parachutes work? What causes whiplash and how do seat belts work? If you get a chance, watch the Julius Sumner Miller videos on Newton’s 2nd law and 3rd law on You Tube. And also, here’s the link to the video clip I showed you on terminal velocity and the Physics of Skydiving I think they’ll all help a lot with the conceptual information

Tomorrow – one last look at the problems, and test Thursday! 🙂


Photo by Sandis Helvigs on Unsplash

Physics 11-8-18 Net Vertical Force

PHYSICS: Great start with net vertical force! Don’t you think it’s the same as horizontal – just turned 90 degrees? And incredible demonstrations of some important concepts! Thank you Payne & Logan, and thank you Joseph! Awesome! I love, love, love watching you make physics come alive!

Physics 11-7-18 Friction & Forces on an Incline Problems Review & Help Session

PHYSICS: Boxes and block, all slipping and sliding… Is it starting to make a little more sense? Here’s our review of of some of the homework problems from today – #36, 40, and 41 (I think). Below the lesson for today is the help session from this morning. It has #46 – the “girl on a sled coasts down a hill” problem.

Here’s the thing. You can watch me or someone else do a thousand problems (okay, maybe not a thousand – but a lot!), and it won’t help. I don’t want you to copy what I do, I want you copy why I’m doing it. Make sense? You’re getting it…keep sledding and watch out for net forces!


flick photo by Eva the Weaver

Help Session

Physics 11-6-18 Friction Problems & Friction on Inclines

PHYSICS: Who knew snow skiing could be so complicated! Well…friction problems on an incline anyway. Here’s our discussion of friction problems on an incline.

Back to the problems – remember, drawing the diagram is super, super important. Label all the forces and apply the concepts you know about net forces and resultant forces – let it tell you a story. 🙂

Here is some info you might find helpful:
Wed night answers


flickr photo by t i g

Physics 11-1-18 Friction & Normal Force

PHYSICS: Why don’t things that are moving just keep moving? Here is our intro on friction from today. Homework UPDATE for Thursday night: Pg. 146 – 149: 30, 32, 35, 37 – 39, 45, 47, 49

Remember a few key things. One of the most important – net forces produce acceleration.

You can find Ff a couple of different ways – it’ll be part of a net force equation and can be found from the coefficient of friction equation. If and ONLY if your object is moving at a constant velocity, Ff will equal Fa. Fn is only sometimes equal to Fw. If your object is pulled at any angle (or pushed), Fn will be a part of Fnet in the vertical direction.

Whew! 🙂


flickr photo by kbaird

Physics 10-22-18 A Gorilla, a Woodpecker & a Look Toward ZORBA

PHYSICS: Did you see it? It’s a gorilla… in a hammock!! Here’s our walk through the gorilla, the woodpecker, and a great preview for the Zorba problems today. Question – were you doing more than just watching me work through the problems? Were you brainstorming, applying information you’ve previously learned?!? That’s what it takes!

Now you try it! Go conquer the Zorba problem!!

Answers for the Equilibrants II worksheet are below:

  1. Fn = 3430 N upward against feet
  2. Fn1 = Fn2 = 1890 N upward on each foot
  3. F forward = 4.59 N
  4. T1 = T2 = 1760 N
  5. T1 = 1360 N and T2 = 680. N


Photo by Jaroslava Petrášová on Unsplash

Physics 10-19-18 And Did the Hammock Crash?

PHYSICS: Great work today thinking through this one and also the “Wanda has a sign” problems! How you look at problems from the beginning can make a huge difference – huh?

A couple of things that work for me when doing equilibrium, etc., problems – first, draw them. Then go back through and separate resultants into components. If an object is in equilibrium, then there are no net forces – all the forces in the x direction balance – everything left equals everything right, and all the forces up equal all the forces down.

You’ve got all the ammo you need, now go forth and conquer!

Answers for the Equilibrants II worksheet are below:

  1. Fn = 3430 N upward against feet
  2. Fn1 = Fn2 = 1890 N upward on each foot
  3. F forward = 4.59 N
  4. T1 = T2 = 1760 N
  5. T1 = 1360 N and T2 = 680. N


flickr photo by Nomadic Lass

Physics 10-18-18 Forces & Equilibrium

PHYSICS: So, how is the balance in your life? Here’s our discussion of net force, equilibrium, and equilibrants. Were you experiencing a little déjà vu? Great job today!

HW update – do Equilibrant Forces WS 1 and, as possible, see if you can get a head start on Equilibrant Forces WS 2 🙂


Image source phoenix.fanster.com/…/2009/08/tug-o-war1.jpg