DEFINITIONS: MECHANICS 1

1. Displacement
   Displacement is distance in a given direction.
   
   
2. Velocity
   Velocity is the rate of change of displacement with repect to time.
   
   
3. Acceleration
   Acceleration is the rate of change of velocity with respect to time.
   
   
4. Velocity-time graph
   A velocity-time graph of a body moving with constant acceleration is a straight line.
   The slope is accelereation.
   The area under the graph is the distance travelled.
   
   
5. The acceleration due to gravity
   In the absence of air resistance, all objects near the Earth's surface,
   if released, will fall downwards with the same acceleration.
   The acceleration is called acceleration due to gravity. Its symbol is g.
   
   
6. Scalar Quantity
   A quantity that has magnitude only and has no direction in space is called a scalar quantity.
   
   
7. Vector Quantity
   A quantity that has both magnitude and a direction in space is called a vector quantity.
   
   
8. The Parallelogram Law
   If two vectors, drawn tail to tail, are the adjacent sides ab and ad of the parallelogram abcd,
   the diagonal from a to c of this parallelogram is their resultant.
   
   
9. The Triangle Law
   If two vectors are drawn head to tail
   the vector from the head of the first to the tail of the second is their resultant.