READ BEFORE EXAM Flashcards
units of mass in f -ma
mass in in kg
determining whether acceleration is negative or positve
When an object is speeding up, the acceleration is in the same direction as the velocity. Thus, this object has a positive acceleration. In Example B, the object is moving in the negative direction (i.e., has a negative velocity) and is slowing down. According to our general principle, when an object is slowing down, the acceleration is in the opposite direction as the velocity. Thus, this object also has a positive acceleration. https://www.physicsclassroom.com/class/1DKin/Lesson-1/Acceleration
2 forces acting in same direction
ADD UP, eg mgsin(theta) and Friction, if they act in same directio, add them up
To ensure somthing remains in equillibrium If something is on the point of slipping
f
common question
“find the force exerted on the pulley by the string”
in pulleys…
its always WEIGHT- TENSION
NOT THE OTHER WAY AROUND
THE GENERAL FORMULA FOR PULLEYS
T- MGsin (Theta) = ma
(use this to equate stuff) ( especially when F is already given )
eg below (the acceleration was already given )
when something hits the ground ( pulley)
there is no longer any tension acting on it
common question: (after object hit ground in pulley)
.work out V from the starting point
.turn that V into U in the second part
note: for simultaneous tension equations etc,
equate them to 0 and solve
IMPORTANT NOTE: In a situation such as this one with two objects suspended over a pulley, the more massive object will accelerate downward and the least massive object will accelerate upward. The magnitude of the acceleration will be the same for each object
+
inextensible= tension is the same throughout
if somethign is on hte point of slipping
f=ur
if its on equillibrium
f
important note for projectile motion
HORIZONTALLY Theres 0 acceleration!
note for “s”
”s” is displacement ( look at paper 3 2018 last question part b) )
