Physics G481

Scalar quantity - has only magnitude (size)

Example: temperature, volume, distance, speed, mass and time

Vector quantity - has both magnitude and direction

Example: force, velocity, acceleration and displacement

Quantities:

• Distance
• Displacement - distance moved in a certain direction (s)
• Speed - change in displacement/ change in time (v)
• Velocity - change in displacement/ change in time (v)
• Acceleration - change in velocity/ change in time (a)

Newton's Second Law         

F = m a

F = total force                M = mass               A = acceleration

Newton

  1N = 1kg x 1ms-2

Aristotle theory:

Heavier objects fall faster

Galileo theory:

All objects (irrespective of it's mass) have the same acceleration.

Two balls of different masses reach the ground at the same time.

Einstien's special theory:

Mass of particles increase as its speed approaches the speed of light (This is why we cannot directly apple F = ma)

Factors affecting drag force:

• Drag ∝ (speed x speed)
• Drag ∝ cross-sectional area
• Drag depends on viscosity (Air temperature)

Terminal Velocity:

• Weight = Drag
• Net force = Zero
• No acceleration