Free Fall Vocab

friction

force that acts between materials that touch and that opposes motion. Depends on the nature of the surfaces in contact (car tire and road). Transforms kinetic energy into thermal energy. opposes motion. if car moves west, friction moves east

subscript f

friction; (always opposing motion)

finding displacement

d=1/2a(change in t)^2

weight

force on an object due to gravitational pull of Earth on an object. Always downward toward center of the Earth. Measured in Newton (N)

displacement

how far something moves; proportional to amount of time

finding mass

m=a/F

mass

measure of inertia of an object. SI unit is kilogram (kg)

force

push or pull that acts on an object because of an interaction between the object and its environment

terminal speed

speed at which the acceleration of a falling object becomes zero because the upward force balances the downward weight force; maximum downward speed

total mass of blocks

sum of the masses of each block

subscript s

support force; always upwards

subscript t

tension; (tension from rope)

terminal velocity

terminal speed in a downward direction. the motion of the falling object is at a constant speed in a straight line therefore acceleration is zero

Free-body diagram

the body is represented by a dot and that shows all the forces acting on a body as pointing outward from the dot. help us see the interaction of all forces on an object, including friction

what causes an object to accelerate?

the cause of acceleration is a non-zero net force

finding average velocity

v=(final velocity-inital velocity)/2

free fall

vertical motion of an object when the only vertical force acting on it is gravity. Can be upward (slows down) or downward (speeds up). GRAVITY IS THE ONLY FORCE ACTING ON THE OBJECT(always acts downward)

weight-to-mass-ratio

weight of an object divided by the mass of an object. always has the same value at the same location, regardless the object. surface of the earth the ratio is 10 m/s^2

net force

combination/sum of all forces that act on an object F=ma

fluid resistance

(or drag force) force exerted by an fluid on an object moving through the fluid; depends on nature of fluid, speed of object and area of the object in the direction of its motion through the fluid; acts in the opposite direction of the moving object. (fluid can be a gas, such as air, or a liquid)

force of gravity (acceleration due to gravity)

10 m/s^2

directly proportional

2 values changing in the same direction, so as one doubles the other also doubles; force is this

Inversely Proportional

Acceleration is this to mass; 2 values changing in the opposite directions, so as one doubles the other is halved

net force (of blocks)

F=ma a=10m/s^2

newton's second law

F=ma; describes motion when the net force is not zero the object accelerates; acceleration of an object is caused by a net force acting on the object, is in the direction of the net force and is limited by the mass(inertia) of the object; when a non-zero net force acts on any object, it must accelerate in the direction of the net force and inversely proportional to the mass of the object that is accelerating. a=F/m

explains the cause of acceleration

a=F/m

finding acceleration

a=F/m a= final velocity-initial velocity/change in time

air resistance

always acts to oppose motion (downward on trip up, upward on trip down); depends on the speed of the object through the air (higher the speed the greater the air resistance) and the are of the object in the direction of its motion through the air (the greater the area, the greater the air resistance)