5a. How will the temperature reading on the thermometer be affected by following the technique shown in the diagram?

5b. How should the thermometer be placed in the beaker to get a more accurate measurement of the solution’s temperature?Answer BOTH A & B! You do NOT have to use full

sentences but DO spell correctly!

BELLRINGER

House Keeping

Supply Check Take attendance Excel info Hand out tickets if applicable Thank you to… Recycling HW: READ CHAPTER 4, PAGES 94-115 in

the book The Curse of Knowledge

FORCES

August 25, 2010

Basic definitions & symbols

∑ = “the sum of” Vector= a straight line representing the

direction of a push or pull (can be added) Newton = the unit of force

N = kg * m s2

“Normal” = perpendicular

Force Concepts

Forces are represented by arrows drawn from the center of mass of the object being analyzed

The length of a vector is proportional to the amount of force used Ex. 1cm = 10 Newtons; 3.5cm = 35 Newtons

NO other vectors are ever drawn from the center of an object (ex. velocity or acceleration) because these other vectors are the RESULT of a force

Every force will have 2 subscripts The first is the object on which a force is applied The second represents the object applying the force

Main Forces

WOE = “weight” = — mg force on an object by the gravity of the earth

NOS = “normal force” = +mg the contact force that keeps objects from

moving through one another ALWAYS at a right angle to the surface of an

object Force on the object by the surface

fOS= “frictional force”= µN ALWAYS parallel to the surface Force on the object by the surface

Main Forces (cont’d)

TOR= “tension force” A tension ALWAYS pulls; can not be applied to

springs Force on an object by a rope

FOA= “applied force” = ma An external force applied to an object This is normally given without saying where it’s

coming from The force on an object by an applied source

***Whenever there is an acceleration, there HAS to be a force***

Free Body Diagram A free body diagram is the visual

representation of force vectors

WOE = — mg

NOS = + mg

FOA = mafOS = µN

∑ Fy = mg - mg = 0∑ Fx = ma - µN = manet

Fnet = manet

Castro’s Guide to Forces

#1 & 2 together 10 minutes to complete #3 & 6 Groups 1, 4, 7 #4 & 7 Groups 2, 5, 8 #5 & 8 Groups 3, 6, 9