Equations 

Chapter 2 equations

1.   Coefficient of friction= Horizontal force/vertical force.

EX. What is the coefficient of friction for a desk with 100 N of vertical force and 500 N of horizontal force?

500 N/100 N

5 Mu

2.   Calculate beginning momentum. (Total momentum before crash=total momentum after crash.)

*Mometum= Mass (velocity)

Object 1 momentum +  Object 2 momentum   = Object 1 momentum +  Object 2 momentum

Mass (velocity)              +  Mass (velocity)         = Mass (velocity) +  Mass (velocity)

Before the crash                                                           After the crash

EX. Object 1 has a mass of 5 Kg and travels at 20 m/s and object 2 has a mass of 50 Kg and travels at 50 m/sec before the crash. How fast is the second object traveling after the crash if object 1 is moving at 100 m/s?

BEFORE CRASH                                              AFTER CRASH

Object 1 mo    +  Object 2 mo  = Object 1 mo +  Object 2 mo 

•          (5Kg *20 m/s)+( 50 Kg *50 m/sec) =(5Kg *100 m/s)+( 50 Kg *?m/s)

•          100 Kg*m/s + 2500 Kg*m/s  =500 Kg*m/s  +  ( 50 Kg *?m/s)

•          2600 Kg*m/s -500 Kg*m/s  =500 Kg*m/s  -500 Kg*m/s  +  ( 50 Kg *?m/s)

•          (2100 Kg*m/s )/50 Kg =( 50 Kg *?m/s)/ 50 Kg

•          ? = 42 m/s

•               Second way to do the problem

•          (5Kg *20m/s)+(50Kg *50m/s) =2600Kgm/s

•          Calculate ending momentum.

•          (5Kg *100m/s)+(50Kg *?m/s) =2600Kgm/s

•          Solve for ? 

•          ? = 42 m/s

•         Chapter 2 workbook pages.  They are 41, 42, 47, 48, 49, 55, 56, 57, 65, 70, and 73.

•         READ pages 53 and 71 for the five facts.

Terribly             T

Giddy                G

Mr.                     M

K                         K

Hollard              h

Don’t                 da

U                         unit(only one letter)

Dare                  d

Call                     c

My                     m

Mom                 µ

Nancy               n

Pancy                p