Forces and Motion Chapter 1 Flashcards
define motion
an objects change in position relative to a reference point
how can you describe the direction of an objects motion
using a reference direction
define speed
distance traveled divided by the time during which the motion occured
give an example of metric and english units used to measure speed
metric- meters/second english- miles/hour
define velocity
the speed of an object in a particular direction
how is velocity different from speed?
it’s the same as speed except velocity uses a reference direction
what can be said about the velocity of an object that is in circular motion?
an object traveling in a circular motion is always changing direction, so it’s accelerating (centripetal acceleration)
define force and give the unit
a push or a pull exerted on an object that changes the motion, expressed in newtons
what is net force?
combination of all the forces acting on an onject
how do you calculate net force when the forces are in the opposite direction?
add them together
how do you calculate net force when the forces are in the opposite direction?
subtract the smaller force from the bigger one
what is the net force when the forces are balanced?
0 newtons
what occurs when forces are balanced?
will not cause a change in motion, will not cause a non-moving object to start moving
what occurs when forces are unbalanced
produce a change in motion, will cause motionless object to start moving
define friction
a force that opposes motion between two surfaces that are in contact
how does force affect friction?
adding more force increases friction
does a rough or smooth surface cause friction and why?
rougher surfaces have more friction because they have more hill/valleys in the surface that can come into closer contact
what effect does surface area have on friction?
none
what is the different between kinetic and static friction?
kinetic is friction between moving objects, static is when force is applied but does cause the object to move
name examples of how friction can be harmful
- cause car parts part to heat up/wear down
- cause holes in socks/jeans
name examples of how friction can be helpful
- allows pencil to leave a mark
- you would slip and fall w/out friction
- helps brakes stop a car
how can you decrease friction?
- use lubricants
- make surfaces smoother
- switch from sliding kinetic friction to rolling kinetic friction
how can you increase friction?
- make surfaces rougher
- increase force pushing surfaces together
define gravity
force of attraction between objects what is due to their masses
what two factors determine gravitational force
mass and distance
define mass and weight
mass- amount of matter in an object
weight-measure of gravitational force exerted on an object
