Notes and vocab Chapter 3
Projectile motion
Throw a baseball and the path it follows is a curve. This curve is a
combination of constant-velocity horizontal motion and accelerated
vertical motion. It is a nonlinear motion-motion along a curved path.
Vector and scalar quantities
Pictures are powerful tools.
Vector quantity: A quantity that requires both magnitude and
direction for a complete description.
Velocity differs from speed in that velocity includes direction in its
description. Velocity is a vector quantity, as is acceleration.
A quantity that can be added, subtracted, multiplied and divided like
ordinary numbers are scalar quantity. Scalar quantity is completely
described by magnitude only.
Velocity Vectors
An arrow is used to represent the magnitude and direction of a
vector quantity. The length of the arrow drawn to scale, indicates the
magnitude of the vector quantity. The direction of the arrow
indicates the direction of the vector quantity. Same rule of
combining arrows as vector. A velocity is sometimes the result of
combining two or more other velocities. Airplane velocity is an
example.
The result of adding two vectors, called the resultant.
The resultant of two perpendicular vectors is the diagonal of a
rectangle constructed with the two vectors as sides.
For the more general case when the vectors are not at right angles to
each other, the resultant is found by constructing a parallelogram.
Component of vectors
Any vector can be resolved into two component vectors at right
angles to each other. These two vectors are known as the
components of the given vector they replace. The process of
determining vector is called resolution.
Projectile motion
Projectiles near the surface of earth follow a curved path that at first
seems rather complicated. But it is simple when we look at the
horizontal and vertical components of motion separately.
The horizontal component of motion for a projectile is completely
independent of the vertical component of motion.
Upwardly launched projectiles
The vertical distance it falls beneath any point on the dashed line is
the same vertical distance it would fall if it were dropped from rest
and had same vertical distance it would fall if it were dropped from
rest and had been falling for the same amount of time.
Horizontal component is always the same and that only the vertical
component changes.
Fast-Moving projectiles-satellites
If the ball is fast enough to follows the curved downward path of
Earth, it will become a satellite.
The minimum speed to become that is 8m/s.