CHAPTER 2 PHYSICS LEC

• Kinematics - Describes motion while ignoring the external agents that might have caused or modified the motion.
• Kinematics - describes the motion of points, bodies, and systems of bodies without considering the forces that cause them to move.
• Types of Motion - Translational, Rational, Vibrational.
• Translational - an example is a car traveling on a highway
• Rotational - An example is the Earth's spin on its axis.
• Vibrational - an example is the back-and-forth movement of a pendulum.
• Displacement - is defined as the change in position during some time interval.
• Displacements - Represented as Ax (Si units are meter (m)).
• Distance - the length of a path followed by a particle.
• Distance is always positive
• Vector quantities need both magnitude and direction to completely describe them.
• Scalar quantities are completely described by magnitude only.
• Average Velocity - rate at which displacement occurs.
• The SI units of Average Velocity is m/s.
• Average Speed = has the same units as velocity, and is defined as total distance/ total time.
• Speed is a scalar quantity
• Instantaneous Velocity - The instantaneous velocity indicates what is happening at every point of time.
• The instantaneous velocity is the slope of the line tangent to the x vs. t curve.
• The instantaneous velocity can be positive, negative, or zero.
• The instantaneous speed is the magnitude of the instantaneous velocity.
• The instantaneous speed has no direction associated with it.
• “Velocity” and “speed” will indicate instantaneous values.
• When an object’s velocity and acceleration are in the same direction, the object is speeding up.
• When an object’s velocity and acceleration are in the opposite direction, the object is slowing down.
• The acceleration of an object is related to the total force exerted on the object.
• The force is proportional to the acceleration
• Negative acceleration does not necessarily mean the object is slowing down.

  (If the acceleration and velocity are both negative, the object is speeding up.)
• The word decelerationhas the connotation of slowing down.
• there are 5 kinematic equations
• Galileo Galilei - Italian physicist and astronomer

  Formulated laws of motion for objects in free fall

  Supported heliocentric universe
• Newton's First Law states that if no net external force acts on an object, then its velocity will remain constant (or it will continue moving at a constant velocity).
• A body in uniform motion tends to stay in uniform motion unless acted upon by an unbalanced force.
• Inertia is the tendency of an object to resist changes in its state of motion or rest.
• An object with greater mass has more inertia than one with less mass.
• If there is no resultant force acting on an object, it remains stationary or moves at a constant speed in a straight line.
• According to Newton’s first law, when a force is applied to an object, it accelerates until all forces have been balanced out.
• A freely falling objectis any object moving freely under the influence of gravity alone.
• The acceleration of an object in free fall is directed downward, regardless of the initial motion.
• The magnitude of free fall acceleration is g= 9.80 m/s2.
• g decreases with increasing altitude