Chap 2- forces, moment, pressure Flashcards
Define force
a push, pull or twist
What can a force change
speed, direction, shape
Which type of quantity are forces
vector
What is used to show forces
arrow with heads
How does the arrow show force
- arrow size - magnitude (size) of force
- arrow head - direction of force
Note: Always label your arrows magnitude
name the 9 types of forces
-friction,
-compression
-tension
-weight
-applied
-air/ water resistance
-magnetic
-electrical
-normal (upthrust, buoyancy for in water)
Name the 6 contact forces
-friction
-applied
-compression
-normal
-air/ water resistance
-tension
Name the 3 non contact forces
-electrical
-weight
-magnetic
Name 2 types of friction
-static
-dynamic
define friction
force that opposes one surface moving or tying to move past another (opposes motion)
define static friction
force that keeps object at rest
define dynamic friction
opposes sliding or rolling motion
When walking on the floor what forces magnitude are equal or not equal to each other
-normal = weight
-thrust is more than resisting force (friction and air resistance combined) because the person is able to moving
Why do we not sink into the floor or float
because normal force is equal to weight
Which is bigger: static or dynamic friction
static friction
Which friction is on a object at rest
static
what is resisting force
force opposing another force
What is resultant force
a single force that can replace all individual forces acting on the object, and have the same effect
How do you find the resultant force
-arrows in same direction = add the forces
-arrows in different direction = minus the forces and the greater force will the the resultant force in the greater force direction
-if minus becomes 0, the resultant force is 0 so stationary
Which directions can a force move in
North, South, East, West and anywhere in between
What are the effects of friction
opposes motion, creates heat
What is the unit for force
Newtons (N)
define Newton’s 1 law
An object will remain stationery ( at rest) or move in a constant (uniform) speed in a straight line unless a net resultant force acts on it
define Inertia
an objects resistance to change in speed and its direction
What is the relationship between Mass and Inertia
As mass increase, Inertia increases
What is the effect of increased Inertia
greater Inertia, more difficult to move the object when stationary or change its speed or direction when moving
What is the mass of a body
measure of Inertia
State Newton’s 3 law
for every action, there is an equal and opposite force on it (forces act in pairs)
Define balanced
forces in opposite directions that have the same magnitude
how does forces always act in
pairs
What does every object with a mass have
a gravitational field
an object with a constant speed has what forces that are?
forward and backward forces that are balanced
When will there be in unbalanced forces
acceleration
define Newton’s 2 law - symbols and words
force = mass x acceleration
F = ma