Mechanics 1

Mechanics 1

1. Scalars and Vectors

   • Mass temperature, time, length, speed, energy,
   • Displacement, force, velocity, acceleration, momentum
   • Use Pythagoras' Theorem to find the resultant force
   • Split vectors into horizontal and vertical components and use trigonometry

2. Free fall

   • Acceleration is a vector - 'g' is vertically downwards
   • The only force acting on an object in free fall is its weight
   • Aristotle
     • 'Heavy objects fall quicker than lighter objects'
   • Galileo
     • 'All objects in free fall accelerate at the same speed'
     • distance is directly proportional to the time taken ^2
     • Rolled balls of different mass down a smooth surface, recording the time it took to reach the bottom
   • Projectile Motion
     • 1) resolve initial velocity into vertical and horizontal 2) solve vertical using linear motion 3) solve horizontal using speed = distance/time

3. Newtons Law of motion

   • As you get close to the speed of light, the mass starts to increase!
   • Displacement - has both a magnitude and a direction
   • Vectors can be resolved into components
     • x-direction: F x cos(angle)
     • y-direction: F x sin(angle)

4. Moments and Torque

   • Force x Perpendicular distance from pivot or Force of one x perpendicular distance between both forces.
   • Couple
     • A pair of forces of equal size which act parallel to each other, but in opposite directions

5. Car Safety

   • Thinking Distane
     • Reaction time, tiredness, alcohol, drugs, illness, distractions.
   • Braking Distance
     • Braking force, friction, mass, speed
   • Seat belts - increase the time that you are brought to a stop
   • Airbags
     • accelerometer is used to detect rapid deceleration
       • This, if triggered, causes a chemical reaction to occur which releases gas.
         • fills the air bag and makes you stop over a longer period of time
   • Crumple zones - absorb some of the energy
   • GPS systems
     • Use trilateration to find your positioning
     • time delay between satellite signal being sent and being received us used to find distance using the speed of light.

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