Flash Card #9
What is force?
push or pull; described by
strength
What is the unit of force?
Newton (N)
What is force represented as?
Force is represented as an arrow (with direction)
longer arrow ~ greater force
What is net force?
combining forces
When do unbalanced forces occur?
Unbalanced forces occurs when a net force is
present causing a change in the object’s
motion.
When do balanced forces occur?
Balanced forces occurs when equal (strength)
forces are acting in opposite directions. The net
force is zero. Balanced forces does not change
the object’s motion.
What is friction?
the force that two surfaces exert
on each other when they rub against each
other.
What are the factors that affect friction?
1) weight
2) rough versus smooth surfaces
3) lubricants (oils, grease); ball bearings
4) surface area
What are the four types of friction?
Static Friction, Sliding Friction, Rolling Friction, Fluid Friction
What is Fluid friction
Friction when an object moves
through a fluid. To reduce friction, use oils &
lubricants; streamline.
What is Static Friction?
friction that acts on objects that
are not moving. Static greater than sliding, rolling,
fluid friction.
What is Rolling friction?
friction when an object rolls
across a surface. To reduce friction, use wheels or
ball bearings.
What is Sliding Friction?
friction when two surfaces slide
over each other.
How is friction helpful?
1] STOP
2] MOVE
3] WARMTH
4] FIRE
How is friction harmful?
1] WEAR OUT PARTS
(watches, engines, shoes, clothing)
2] FIRE (reentry from space)
3] REDUCES EFFICIENCY
What is gravity?
an attractive force between
objects containing mass.
What are the factors of gravity?
Mass and Distance
What is Mass?
amount of matter (atoms) in an object
What is distance?
length between two points
increase mass ~ increase gravity
increase distance ~ decrease gravity
What is Terminal Velocity?
maximum velocity of a
free falling object occurs when the force of air
resistance equals the weight of the object.
Terminal velocity represents balanced forces
where upward air resistance equals downward
gravity.
What is Projectile motion?
an object that is thrown. A projectile
(with horizontal motion) will fall at the same rate as
any dropped object.
What is free fall?
only gravity acting on a falling object. Objects
accelerate as they free fall because gravity is an unbalanced
force. In a vacuum, all objects in free fall accelerate at the
same rate regardless of their masses. Gravitational
acceleration near Earth is 9.8 m/s2.
What is air resistance?
is a type of fluid friction as an object
falls through the air. Greater surface area of object ~
increase in air resistance ~ slower the object falls. Air
resistance increases as velocity increases.
What are action and reaction pairings?
jumping
paddling
