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The Fun Side of Mechanics

By Jonathan Abbott. The Fun Side of Mechanics. My Goal and Yours. My goal for you is to be better prepare you to understand mechanics in the real world. I want you to have a conceptual grasp of the concepts. I want you to have familiarity applying the concepts mathematically.

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The Fun Side of Mechanics

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  1. By Jonathan Abbott The Fun Side of Mechanics

  2. My Goal and Yours • My goal for you is to be better prepare you to understand mechanics in the real world. • I want you to have a conceptual grasp of the concepts. • I want you to have familiarity applying the concepts mathematically. • I want to bridge and build up your schemas.

  3. Few Background Things • Know that we are starting off easy and then building up. • Ask questions often. I may stop for questions. • Try this at home! –But be careful! • We will have homework. I encourage you to do it.

  4. WHAT’s Mechanics anyway?(Remember, we’re starting easy) • Dictionary.com® says physics is “thebranch of physics that deals with the action of forces on bodies and withmotion, comprised of kinetics, statics, andkinematics” • My definition for physics is: • Geometry in Motion.

  5. What’s in Motion? • That would be MATTER. • Mass is a property of an object. • We say an object that has mass is matter. • Confusing, no? • If someone weighed 155 lbs., they would have a mass of about 70 kg. • Would mass would they have if up in space?

  6. Inertia • Something that has a lot of mass has a lot of inertia. • It’s hard to get something moving or bring it to a stop. • Might this make unicycling easy?

  7. Gravity • Gravity is a force. • Welcome to reality.

  8. Newton’s First Law • Newton’s First Law: An object in motion will stay in that motion until acted upon by a force. • In other words, I just keep riding forward. • Just keep pedaling, just keep pedaling… You saw this Yourself

  9. Tug of War Time! Grrrrr….. • Need two amazing volunteers. • Be nice: we want to learn about net force.

  10. Forces, forces everywhere! • Contact Force: Hitting the ground • Field force: Like gravity

  11. Safety: Hurts when you fall! • The contact force between you and the ground can hurt! • Helmet • Wear it, love it, and it will love you back!

  12. Newton’s Second Law • Force causes an acceleration • A larger mass takes more force to cause the acceleration • Force = Mass * Acceleration • F=mA • Two-object drop! • What if parachute?

  13. Challenge! • Demonstrate Newton’s First and Sec0nd Law with the objects provided. • Newton’s First Law: An object in motion (or rest) tends to stay in that same motion (or in rest) until acted upon by a net force • Newton’s Second Law: Force = Mass * Acceleration

  14. Like to Accelerate? • Acceleration is speeding up or slowing down. • Can acceleration be negative? • What if I turned a corner, but had the same speed? • Let’s define acceleration as the rate of change in velocity

  15. Scalar vs. Vector

  16. Vectors are Audacious • *cough, cough* I mean bold-faced. • F = m A • Or we put a little arrow overtop or a squiggly underneath.

  17. Units give us utility • SI: International System

  18. Force Diagrams 1.0 & Components

  19. A little Trig • Alex pulls a 10 kg sled at 60 degrees above the horizontal with a force of 30 Newtons. How fast does the sled accelerate? • How fast will the sled be going in 3 seconds?

  20. Damathy stuff: Derive Equations • We will use that • Δx = v * Δt • Δv = a * Δt • To get: • Vf= Vi + a * Δt • Δx = vi * Δt + (½) a * (Δt)2 • (Vf)2 = (Vi )2 + 2(a * Δx)

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