1. Find 17 creatures in this paragraph
Kneel in the kayak grasping the boat, but don't wrench the bullion or scowl at the chart. Behind the taped and sealed planter is a benevolent collier. The foxglove is in the bath.

2. Dawson High School Physics
Everyday Forces
Dawson High School Physics

3. Force of Gravity and Weight
The force of gravity is represented by Fg
Fg is a vector quantity.
Fg always points down toward the center of the Earth.
The scalar portion (magnitude) of the force of gravity is what we call weight.
Use spring scale to work out that Weight = mass x g

4. Weight and Mass
Mass is a measure of the amount of matter an object has.
It also tells us how much “inertia” an object has.
Weight is a measure of the force of gravity.
In the absence of gravity, a substance has no weight, but it still has mass.
Mass is proportional to weight.
Weight = m g

5. Normal Force
The normal force is the force that a support surface provides.
This force is always perpendicular to a surface.
Ex.- A .50 kg book rests on a table. Fn
Fg=-mg= N

6. Normal Force
The normal force is not always equal to an object’s weight.
Example- A student presses down on with a force of 3 N on a 4.9 N book. Fn
Fg=-mg= N
Fs = -3 N

7. Frictional Forces Frictional forces oppose the applied force.
They act in the opposite direction of the motion.

8. Static Friction
Static friction (Fs) is the frictional force that acts on a static (nonmoving) object.
When an object is not moving, the frictional force will equal the applied force but be in the opposite direction.
Fs= - Fapplied
There is a maximum amount of static friction, Fs,max . Once the applied force exceeds Fs,max the object breaks free and begins moving.

9. Kinetic Friction
Kinetic friction is the frictional force on a moving object.
The force of kinetic friction is less than the maximum static friction.
The net force on a moving object is equal to Fapplied - Fk

10. Coefficient of Friction
The force of friction is proportional to the normal force.
The coefficient of friction is the ratio of the force of friction to the normal force for particular surfaces.
Coefficient of kinetic friction mk = Fk/Fn
Coefficient of static friction ms = Fs,max/Fn

11. Coefficient of Friction Example
A 24 kg crate, initially at rest, requires a 75 N force to set it in motion. Once moving, a force of 53 N is needed to keep it moving with constant velocity.
Find the coefficient of static friction and the coefficient of kinetic friction.

12. Coefficient of Friction Example

13. Coefficient of Friction Example

14. Air Resistance The force of air resistance (FR) is a form of friction.
FR depends on velocity.
Terminal speed: At some speed, the air resistance will be equal in magnitude to the force of gravity. (FR = -Fg). Once an object reaches that speed, it will no longer accelerate. It will continue to fall at a constant speed.