forces Flashcards
examples of contact forces
frictional force tension force drag force/air resistance normal force applied force
surfaces friction work on
all states of matter
what happens when friction causes things to heat up?
it restricts movement
what way does friction move
opposite direction
factors affecting frictional force
- roughness of the surfaces in contact
- magnitude of the forces pressing the surfaces together
- independent of the area of contact
ways to reduce friction
apply lubricant
use streamlined shapes
use ball bearings
smooth surfaces
non contact forces
gravitational force
magnetic force
electrostatic force
what are electromagnets used for?
separate iron and steel from scrap metal piles
uses of magnetic force in transportation
magnets in the train and track repel and lift the train a few centimeters above the track; friction is reduced; allows the train to move fast
force acting on positive and negative charges
electrostatic force of attraction
force acting on the negative charges
electrostatic force of repulsion
what are the electric charges that do not flow in an electric circuit called?
static electricity
weight and mass difference on moon and earth
the weight of an object on the moon is 1/6 its weight on earth while the mass of an object is the same everywhere.
what is the space surrounding the earth where gravity is experienced called?
gravitational field
equation relating mass and weight
w = m * g
equation for pressure
Pa = N / m2
what is speed?
a measure of how fast someone or something moves
SI unit of speed
m/s
equation for speed
speed = distance / time
how is the resultant force represented?
double arrow
how can pressure be increased?
decreasing area
how can pressure be decreased?
increasing area
factors that affect liquid pressure
liquid depth
liquid pressure
what happens when we go higher?
air pressure decreases
what is the air pressing on us in all directions known as?
atmospheric pressure
why do underwater vehicles be very strong to withstand the water pressure?
the water pressure deep in the ocean is very strong
why is the dam thicker at the bottom than at the top?
liquid pressure increases with depth. the pressure at the bottom of the reservoir is greater than at the top. The dam is thicker at the bottom to withstand the greater pressure.
answering tech for water pressure
( recall fact ) + ( relate back to question )
answering tech for force
( highlight the variable that has changed ) + ( relate back to formula and effect on pressure ) + ( highlight effect of change )
why is water delivered to and stored in tanks at the top of most high rise buildings?
causes water in pipes below the tanks to be at a high pressure and ensures that water flows to the units below
changes in air pressure
- squashing a juice box
- hold a suction cup on the wall
- cause difficulty breathing
describe squashing a juice box
- lower air pressure in straw
- higher atmospheric pressure outside the straw pushes the liquid up
describe suction cup on wall
-atmospheric pressure acting on the suction cup holds it tightly on the wall
describe how force causes difficulty in breathing
an aircraft can fly at great heights where the air pressure is low. air is pumped into the aircraft so that the air pressure inside is similar to that near the ground. without this, passsengers will have difficulty breathing
