Types of Forces

• Normal Force (FN)
• Gravitational Force (FG)
• Tension Force (FT)
• Frictional Force (FF)

Steps for force diagrams:

Step 1- Don't panic- Please it does nothing

Step 2- Look at the picture or draw a picture. Be sure to focus on all of the individual reactions

Try to think about what would happen if just that force was acting on it.

Step 3- think about what is causing each of the forces you have identified in step 2- if you can't think of the physical object causing that force it probably doesn't actually exist.

Step 4- Draw your force vectors- scale them appropriately. Larger magnitude vectors should be longer than smaller magnitude vectors

The direction you draw your vectors is important

Like vectors add up, vectors pointing in opposite directions subtract

Step 5- Break your vectors into components if your vector is 2 dimensional. The force vectors should be broken up to have a horizontal and vertical component. You only need to do this if you have vectors pointing in 2 dimensions (both x and y at some angle)

Step 5.5- draw a component diagram- your equations should be based off of this and NOT the actual force diagram when applicable

Step 6- Think about if the vectors balanced or unbalanced

Unbalanced forces cause an object to accelerate- for example, dropping anything causes it to accelerate towards the ground because of an almost constant force of gravity

Balanced forces are where the sum of the vectors pointing to the left are equal to the sum of the vectors pointing to the right OR the sum of the vectors pointing up equal the sum of the vectors pointing down

Step 6- Write an equation to describe the forces. When balanced, the sum should add up to zero. When unbalanced you will have accelerations happening.

Step 7- Plug in values and apply applicable equations. For example, the force of gravity is mass*9.8 m/s/s or mass*9.8N/kg

Remember, mass is measured in kg.

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Mass is a measured of the amount of matter (stuff) that makes something up. It is universal and doesn't change

The force of gravity or weight is a measure of the amount of stuff present in a gravitational field

When you stand on a scale it tells you how much the floor needs push up on you to hold you in place. Scale readings can change if the scale is accelerating. However your force of gravity doesn't change.

Your weight can change depending on the gravitational field you are in. If you weighed yourself on the moon you would weigh different. However you would have the same mass.

Newton's first law of motion- The law of inertia- An object in motion will stay in motion and an object will stay at rest until acted upon by an unbalanced force.

Newton's Third Law of Motion- For every action there is an equal and opposite reaction.

Force from A on B will be equal to the same type of Force from B on A but pointing in the opposite direction

F_AonB = -F_BonA

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Helpful Links

Visuals of how forces interact

http://eschooltoday.com/science/forces/balanced-forces.html

Physics classroom

http://www.physicsclassroom.com/class/newtlaws/Lesson-1/Balanced-and-Unbalanced-Forces

Gravity

https://www.youtube.com/watch?v=YyJSlcIbd-s

A simulator

https://phet.colorado.edu/en/simulation/forces-and-motion-basics

Newton's Three Law's Hyper Physics

http://hyperphysics.phy-astr.gsu.edu/hbase/Newt.html

Newton's Third Law

http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law

A simulator

http://zonalandeducation.com/mstm/physics/mechanics/forces/newton/newtonLaw3.html

Youtube clip of the third law

https://www.youtube.com/watch?v=EgqcGrB3re8

********Breaking Gravity into components

http://www.studyphysics.ca/newnotes/20/unit01_kinematicsdynamics/chp06_vectors/lesson25.htm

http://www.physicsclassroom.com/class/vectors/Lesson-3/Inclined-Planes

http://www.dummies.com/education/science/physics/finding-the-force-of-gravity-along-an-inclined-plane/

for this one they use mg to represent the force of gravity - g= 9.8 m/s/s