Kinematics. Kinematics is the branch of physics that describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion. Kinematics.
Acceleration is a vector quantity. It has both magnitude and direction
A motorcycle is traveling north at 20 m/s. At the end of two seconds it's velocity is 40 m/s North. What was its acceleration during the two seconds?
Distance is a scalar measure of the interval between two locations measured along the actual path connecting them.
Displacement is a vector measure of the interval between two locations measured along the shortest path connecting them.
Mathematical relationships between distance speed velocity and acceleration.
We will use the following symbols: An arrow above a symbol indicates that it is a vector quantity
The basic relationships
For a situation where the initial speed or the initial velocity is equal to zero, the following relationships hold.
When an object is in free fallit means that the only force acting on it is the force of gravity. On earth this means that we must ignore the resistance of air. This is a good approximation if anobject has a smallsurface area, a high density, and is not moving very fast. For example the approximation works well for a dropped steel sphere, but not for a dropped tissue.
Near the surface of the earth a falling object accelerates downward with a constant acceleration. This acceleration is equal to . Frequently we use a rounded value of for calculations. This acceleration is referred to as acceleration due to gravity and is represented by a lowercase g.