Force Flashcards

1
Q

what is force?

A

force is a push or pull movement

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2
Q

what does force cause?

A

accelerations

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3
Q

A force caused by gravity

A

W- weight

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4
Q

A force in a rope or cable

A

T- tension

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5
Q

A force caused by a object in contact with another surface

A

N- normal force

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6
Q

A force that opposes motion of an object

A

F-friction

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7
Q

3 steps to solving elevator problems

A
  1. sketch free body diagram
  2. write down given and unknowns
  3. EFy -> up-down = ma or 0
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8
Q

when will up-down = ma

A

when there is an acceleration

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9
Q

when will up-down= 0

A

when there is a constant speed

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10
Q

what is g’s value

A

positive 9.8

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11
Q

if an elevator is going up and speeding up then…

A

Vf>Vi because it got faster and thge acceleration is positive

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12
Q

if an elevator is going up and slowing down then…

A

Vf<Vi because it is slowing down and acceleration is negative

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13
Q

if an elevator is going down and speeding up then…

A

Vf>Vi because they are both negative and the acceleration is negative

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14
Q

if an elevator is going down and slowing down then…

A

Vf<Vi but they are both negative and the acceleration is positive

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15
Q

If there is constant speed there must be?

A

friction

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16
Q

horizontal, Fx=?

A

right-left= ma

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17
Q

vertical, Fy=?

A

up- down= ma

18
Q

terminal velocity

A

the maximum speed an object can go in free fall

19
Q

with atwood machine problems the differences in mass cause?

A

acceleration

20
Q

newtons third law

A

for every action there is an equal yet opposite reaction

21
Q

example of an action-reaction force pair

A

ball hits bat, bat hits ball with equal force
man runs into wall, wall pushes against man with equal force

22
Q

unbalanced forces cause…

A

acceleration

23
Q

newtons first law

A

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

24
Q

inertia

A

tendency of object to resist any change in its motion

25
how is inertia measured?
by mass in Kg
26
newtons second law
acceleration of an object is directly proportional to the net force acting on it and inversely to its mass
27
equation for newtons second law
Fg=ma
28
forces cause...
accelerations
29
accelerations change...
velocities
30
friction
a force caused by interaction of body with its surroundings -opposes the motion of an object
31
if Fs=F
the object will not move
32
if Ff=Ft
object will move at a constant speed
33
Fs=?
static (stationary) force of friction
34
Fk=?
kinetic (moving) force of friction
35
object moves if...
F is greater than Fs
36
kinetic friction is always ____ than static friction
less
37
Ff(s) equation
u x Fn
38
Ff(k) equation
u x Fn
39
as a ramp becomes steeper static friction must...
increase
40
constant speed means what?
equilibrium