GLO 4 and 5: Circular Motion and Work/Energy Flashcards
in uniform circular motion, what is the direction of velocity?
tangent to the circle
in uniform circular motion, is the magnitude of velocity constant or not?
constant speed
in uniform, circular motion, what is the direction of acceleration?
always towards the centre of the circle
what is the period?
the amount of time it takes to do one cycle is called the period of revolution (T)
what is frequency?
frequency is the number of of revolutions an object does per unit of time f=1/T
what are keplers 3 laws?
- all planets travel around the sun in elliptic orbits, with the sun at 1 focus
- planets sweep out equal areas in equal amounts of time (planets travel faster when closer to the sun)
- T^2/r^3 = constant
how is kinetic energy relate to net work?
if positive net work is done:
- the system speeds up
- the system gains kinetic energy
if negative net work is done:
- the system slows down
- the system loses kinetic energy
positive work is done when:
- displacement and the applied force active in the SAME directions
- energy is ADDED to the object
- the force acts to INCREASE the object’s speed
negative work is done when:
- displacement and the applied force act in OPPOSITE directions
- energy is REMOVED from the object
- the force acts to DECREASE the object’s speed
mechanical energy:
is the energy of moving objects
in work, when is there a gain in energy?
push, pull, thrust
in work, when is there a loss in energy?
friction, air, heat
when the angle between the direction of the motion and an applied force is less than 90 is the work positive or negative?
positive, when the angle is less than 90 the work done is positive
when the angle between the direction of the motion and an applied force is greater than 90 is the work positive or negative?
negative, when the angle is GREATER than 90, the work done is negative
