Sunday, January 29, 2017

Final Exam Review Answer Key

Key, final exam review

1. look these up   
2. see lab work and HW for help  
3. -9.8m/s^2  
4. a) -2.5m/s  b) it is constant, -9.8m/s^2    c) 0.25sec   d) 0.32m     e, f, g) see lab from first semester
5. 131N
6a) 0.55sec   b)0.22m
7.a) see chapter 4, Free body and force diagrams   b) >98N
8. a) 225 Ns    b) 4.5m/s    c) 506 Joules
9.  1125N
10. a) 4.5m/s^2  b)0.63 s
11. 0.15 Joules
12. a)441Joules  b) 0.78 sec   c) 7.7 m/s   d) 441 Joules
13. a) 29.4N    b) 0N
14. a) 12N    b) kinetic    c) 0.4
15. a) 25.5N b) 14.7N  c) static
NOTE: if this is on the final, I'd include a diagram of the ramp and ramp equations.
16. a) m1v1’=-m2v2’   b) 0 Joules     c) -13 kg*s   d)50s
17. 77.6m  
(this problem will NOT be on the final IN THIS FORMAT- it combines about all of the physics of semester 1 to solve this- if you can solve it, you're going to ace the final.  If it is on the final, it'd be broken down into about 10 smaller questions... PE at top gives you total ME through out, then calculate force of friction and work done by Friction- note slope here, and work done by increasing PE by going UP small ramp, use that to find jump velocity, then this is a 2d kinematics question w/ horizontal and vertical velocity from ramp jump velocity at an angle... to determine that the skier lands 77.6m from the ramp.... phew.)


Wednesday, January 25, 2017

!!!More Work (and Energy)!!!

perfect topic for the end of term, isn't it?
MORE work and ENERGY.
HW assignment due 1/27, Friday

Tuesday, January 24, 2017

Puck Lab

Here's the video we'll analyze in class on 2/7

Sunday, January 22, 2017

Semester 1 FINAL Practice Problems

Parkour photography by Johnathan Lucas
SEMESTER 1 PRACTICE PROBLEMS

Equations we've used this semester.  
This list will also be given to you on the day of the final.
Please let me know if you see any equations missing from this list.

STUDY WELL.

Thursday, January 19, 2017

ANSWER key for Newton's Law (chapter 4) HW

See question 9b.
Birthday cake.
Forces.
Life in Balance. 
Here's the key for Chapter 4 questions. 
THERE WILL BE A QUIZ MONDAY, 1/23.

Saturday, January 14, 2017

Impulse & Momentum


Overview: Impulse & Momentum (Physicsclassroom.com)- very similar to lecture given in class on 1/19/2017.

First assignment: Momentum Master Equations

Second Assignment: Impulse & Momentum Practice Problems

WHAT IS A "MASTER EQUATION"? 
these assignments are asking you to manipulate the conservation of momentum equation (m1v1+m2v2 = m1v'1 + m2v'2) so that any variables that can be crossed off or simplified based on the initial and final conditions. 

For example,  
Write a master equation for this scenario:
2 carts have equal mass.  One is pushed and collides with the second cart, which had been at rest.  
You don't know the actual mass or velocities, but you are to simplify the expression to create a 'master equation'.

m1v1 + m2v2 = m1v'1 + m2v'2
we can eliminate several parts of this expression because of the conditions outlined above.

before the collision:
the second cart is not moving before the first cart hits it, so, v2 is 0, so m2v2 is also 0.
the initial conditions can be simplified to:   m1v1

after the collision,
the carts stick together, so they have the same velocity.  v'1=v'2
they also have the same mass.  m1=m
so the after the collision side of this expression can be simplified from m1v'1 + m2v'
to 2mv'  (2x mass of cart 1 X final velocity).

The entire master equation for this collision is:
m1v1= 2m1v'

Thursday, January 5, 2017

HW: Chapter 4

You might not recognize this,
but, we do in fact have a text book.
questions due 1/12
pages 151-157
#6, 8, 9, 10, 23, 24, 27, 55, 56, 59, 67

HERE IS A LINK TO PAGES 151-157
(none of the questions is on page 156, so I didn't scan that one).

Quiz the last half hour of the period on 1/12.
These questions with only numbers and names changed to protect the innocent.

ASE Summer Internships through Saturday Academy.

You should apply.
Really.
Great.
Opportunity.
Also go to a winter info session before the March deadline.

Wednesday, January 4, 2017

Coefficients of Friction and some other random frictional accounts

This posting is just for the curiosity factor.

First, here's a list of some coefficients of friction. (mu).

Each year, scientific studies are nominated for Ig Nobel Awards- which "honors achievements that cannot or should not be reproduced".  In 2003, the winning study was titled "An Analysis of the Forces Required to Drag Sheep over Various Surfaces."  
sheep found 2000m above sea level in a New Zealand snow storm,
being dragged to safety.

Tuesday, January 3, 2017

Friction Lab

Friction Lab Directions & Write up Explanation

measuring the coefficient of friction along a conveyor belt.
http://www.drylube.co.uk/customers/measuring-coefficient-of-friction/
And... because it looks like F=uN, doesn't it?