Nat 5 Physics Dynamics and Space

Space
1. A satellite is an object which orbits another object
Vectors and Scalars
1. Average speed is the distance per unit time
  1. speed= distance /time
2. Instantaneous speed is the average speed of something over a small distance
  1. speed=distance/time
3. Scalar Quantities are defined by magnitude (size) only
  1. Scalar Quantities include distance, speed, time, mass, energy and volume
4. Vector quantities are defined by magnitude and direction
  1. Vector Quantities include displacement, velocity, acceleration, force and weight
5. Distance is a scalar quantity and displacement is a vector
  1. Displacement is the distance and the direction
6. ALWAYS add vectors nose to tail
7. Velocity is the speed of something in a particular direction
  1. velocity = displacement/ time
8. Acceleration is the change in velocity per unit time
  1. Acceleration= final velocity-initial velocity/ time
    1. If a car is slowing down the acceleration is negative
9. The area under a speed time graph is the distance and the area under a velocity time graph is the displacment
Newtons Laws
1. Force can change the speed, direction or shape of an object
2. Unit of force is Newtons (N)
3. Forces are vector (direction and size)
4. Mass is the amount of matter that an object has and weight is the force that gravity exerts on an object- weight is a force
  1. Gravitational field strength is the weight per unit mass
    1. weight= mass x gravitational field strength
    2. Earth 9.8 N/kg
5. Friction is a resistive force which opposes the motion of an object
  1. Friction is a force which acts between two rough surfaces
    1. Friction can be decreased by lubricating the surfaces, separating the surfaces and streamlining
    2. Friction can be increased by choosing surfaces which cause high friction and increasing surface area and choosing shape to increase air friction
6. Newtons 1st Law - an object in motion stays in motion and an object at rest stays at rest unless acted on by an unbalanced force
  1. no force is equivalent to equal forces
    1. For a moving object if the forces are balanced then it will move at a constant velocity
    2. For an object at rest if the forces are balanced it will not move
7. Newtons 2nd Law- if an unbalanced force acts on an objects then the object will accelerate in the direction of the force
  1. The greater the resultant force the greater the acceleration
    1. The smaller the mass the greater the accelaration
      1. Unbalanced Force= mass x acceleration
8. The acceleration of something falling vertically is always 9.8m/s^2
9. Newtons 3rd Law - For every action there is an equal and opposite reaction
  1. Forces occur in pairs. These two forces are always equal in size but opposite in direction
    1. If object A exerts a force (the action) on object B then object B will exert an equal and opposite (reaction) force on object A
      1. F1=--F2
10. A projectile is an object that has been given a forward motion but which is also pulled dowards by the force of gravity this results in the path being curved
  1. Projectile has both horizontal and vertical motion
    1. A projectile travels at a constant speed horizintally and a constant acceleration downwards (9.8)

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Nat 5 Physics Dynamics and Space

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