Motion and Forces Flashcards
what is a place or object used for comparison to determine if something is in motion?
reference point
how do you know if an object is in motion?
If it changes position relative to a reference point.
in science, what system is used to measure distance, mass, volume?
International System of Units (metric)
the standard unit to measure distance
meter
1,000 meters
kilometer
1/100th of a meter
centimeter
how many millimeters make a centimeter?
10
what is the term for the distance an object travels per unit of time?
speed
what is the formula for speed?
S=D/T
how to you determine average speed?
divide the total distance traveled by the total time traveled
what is the term for speed in a given direction?
velocity
to graph motion, how would the axes be labeled?
time on the x axis and distance on the y axis
on a graph, what tells you how fast distance changes in relation to time?
the slope
on a distance-versus-time graph, what does a steep slope tell you about the speed of the object?
the steeper the slope, the faster the speed
on a time distance graph, what does a flat line indicate about the speed?
the speed is zero
what is the term for the rate at which velocity changes?
acceleration
how can you tell if an object is accelerating?
if it changes speed, changes direction or decreases the speed
speeding up means
accelerating
if you calculate the change in speed per unit of time, you are measuring…
acceleration
what SI units are used for acceleration?
m/s/s or m/s2
what is the formula for acceleration?
A=final speed - initial speed/ time
if the final speed is 60m/s and the initial speed is 0m/s and the time of travel is 10 s, what is the acceleration?
6 m/s/s or 6 m/s2
on an acceleration graph does a flat line mean the object is not moving?
No, it just means that it is not accelerating…the speed is constant.
what does a curved line on a distance vs. time graph indicate?
the object is accelerating
a push or a pull
a force
what 2 factors describe a force?
strength and direction
what units measure force?
newtons
on a graph, how are the strength and direction of a force shown?
by vectors
the combination of all forces acting on an object is called
net force
when forces are pushing or pulling in the direction, they are combined forces and what math function would you use to determine the net force?
addition
when forces are pushing or pulling in an opposite direction, they cancel one another out to some degree. what math function would you use to determine the net force?
subtraction
if opposing forces are of equal strength, is there any motion?
nope…they are balanced
which forces can cause an object to start moving, stop moving, or change direction?
unbalanced
equal forces acting on one object in opposite directions are called
balanced forces
the force that two surfaces exert on each other when they rub against each other is called
friction
what determine the force of friction?
how hard the surfaces push together and the types of surfaces involved
which would produce more friction, sandpaper or water?
sandpaper
why are roads scattered with sand in winter time?
to improve friction and provide traction
in which direction does friction work compared to motion?
the opposite direction
friction that acts on objects that are not moving is called
static
type of friction that occurs when two solid surfaces slide over each other
sliding friction
type of friction of marbles rolling across a floor
rolling friction
slipping on a banana peel type of friction
sliding
riding a bike down a hill type of friction
rolling and fluid
type of friction swimming in a pool
fluid friction
the force that pulls objects toward each other
gravity
law that states that the force of gravity acts between all objects in the universe
law of universal gravitation
does gravity act everywhere in the universe?
yep…everywhere that there is mass
what two factors affect the gravitational attraction between objects?
mass and distance
which exerts a greater gravitational attraction…an elephant or a mouse (given equal distances)
an elephant because it has greater mass
which exerts a greater gravitational attraction …a mouse in the next room or an elephant across the universe?
the mouse because it is so much closer
