Force Flashcards
what is force?
force is a push or pull movement
what does force cause?
accelerations
A force caused by gravity
W- weight
A force in a rope or cable
T- tension
A force caused by a object in contact with another surface
N- normal force
A force that opposes motion of an object
F-friction
3 steps to solving elevator problems
- sketch free body diagram
- write down given and unknowns
- EFy -> up-down = ma or 0
when will up-down = ma
when there is an acceleration
when will up-down= 0
when there is a constant speed
what is g’s value
positive 9.8
if an elevator is going up and speeding up then…
Vf>Vi because it got faster and thge acceleration is positive
if an elevator is going up and slowing down then…
Vf<Vi because it is slowing down and acceleration is negative
if an elevator is going down and speeding up then…
Vf>Vi because they are both negative and the acceleration is negative
if an elevator is going down and slowing down then…
Vf<Vi but they are both negative and the acceleration is positive
If there is constant speed there must be?
friction
horizontal, Fx=?
right-left= ma
vertical, Fy=?
up- down= ma
terminal velocity
the maximum speed an object can go in free fall
with atwood machine problems the differences in mass cause?
acceleration
newtons third law
for every action there is an equal yet opposite reaction
example of an action-reaction force pair
ball hits bat, bat hits ball with equal force
man runs into wall, wall pushes against man with equal force
unbalanced forces cause…
acceleration
newtons first law
an object at rest will remain at rest and an object in motion will remain in motion with constant velocity unless acted on by a net external force
inertia
tendency of object to resist any change in its motion
how is inertia measured?
by mass in Kg
newtons second law
acceleration of an object is directly proportional to the net force acting on it and inversely to its mass
equation for newtons second law
Fg=ma
forces cause…
accelerations
accelerations change…
velocities
friction
a force caused by interaction of body with its surroundings
-opposes the motion of an object
if Fs=F
the object will not move
if Ff=Ft
object will move at a constant speed
Fs=?
static (stationary) force of friction
Fk=?
kinetic (moving) force of friction
object moves if…
F is greater than Fs
kinetic friction is always ____ than static friction
less
Ff(s) equation
u x Fn
Ff(k) equation
u x Fn
as a ramp becomes steeper static friction must…
increase
constant speed means what?
equilibrium
