Forces

Forces

Forces and work done
1. Scalar
  1. Speed
  2. Distance
  3. Overall
2. Vector
  1. Velocity
  2. Displacement
  3. In a certain direction
3. Contact forces touch the object
4. Non-contact can act without touching the object, e.g. gravity
5. Resultant force diagrams
  1. If forces cancel out, the object doesn't move
6. W.D = force * distance
Stretching and turning
1. Deformations
  1. An elastic deformation is one which returns to its origional shape
  2. An inelastic one is one that doesn't return to its original shape
2. The spring constant is k when force = k*extention
  1. found in force-extension graphs by the gradient
  2. Are under the graph = elastic energy stored
3. Moments
  1. Moment of a force = force * distance
  2. Bigger distance = bigger force
  3. for an object to balance, the clockwise and anticlockwise moments must be the same
4. Gears rotation changes for each gear connected
Pressure
1. pressure = force / area
2. measured in pascals
3. Pressure increases the deeper you are in a liquid as there is more liquid on top of you
  1. Pressure(pa) = depth(m) * density(kg/m^3) * gravitational field strength(N/kg)
4. Upthrust occurs when the pressure at the bottom of an object is greater than the pressure at the top
5. Atmospheric pressure decreases with height
Motion
1. displacement is the distance from one point to another in one direction
2. distance is how far something has traveled
3. Acceleration = velocity/time
4. Uniform acceleration means accelerating at a constant rate
5. The gradient of a distance-time graph = speed
6. The gradient of a velocity-time graph = acceleration
7. Terminal velocity is the speed at which the deceleration from air resistance = acceleration from gravity so an object stops accelerating
8. Newtons laws
  1. An object needs a force to move
  2. Acceleration is directly proportional to resultant force
  3. each action has an equal and opposite reation
9. Inertia is the tendency for an object's motion to remain unchanged
Car safety and momentum
1. Stopping distance = thinking distance + braking distance
2. reaction times
  1. factors
    1. speed (both the distance over time and the drug)
    2. Reaction time
      1. tiredness
      2. drugs
      3. alcohol
  2. average reaction times
  3. Tests
    1. Drop a ruler unexpectedly and see where they catch it
    2. Identify when colour changes and how long it was since the colour actually changed
3. Breaking time factors
  1. Speed (not the drug this time)
  2. weather
  3. Tyre condition
  4. How good the brakes are
4. Momentum is vector
5. Cars are designed to stop a person over a longer period of time to make the force lower

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	Criado por Brodie McMeowface quase 8 anos atrás