28 terms

# Motion, Forces and Energy- Nechita

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position
The location of an object, the particular portion of space occupied by a physical object.
reference point
A place or object used for comparison to determine if an object is in motion. Example is a starting line.
speed
The distance an object travels in a specific time. The formula is distance divided by time or d/t
velocity
Speed in a specific direction Ex: 27m/s East
motion
An object's change in position relative to a reference point
equation for speed
speed = distance/time
equation for acceleration
the change in velocity divided by the time it took to make the change. (Vf-Vi)/time where Vf is final and Vi is initial (beginning)
positive acceleration
An increase in velocity over time
negative acceleration
A decrease in velocity over time
force
A push or pull exerted on an object in order to change its' motion. Gravity exerts a force on a mass (kg) called weight (N).
gravity
a force of attraction that is between objects that is due to their masses. The closer together or the greater the mass, the more the attraction.
pressure
the amount of force exerted per unit area of a surface
slope of a distance time graph
Gives the speed of an object. Divide distance at a point by time at that point.
Newton's 1st Law - Law of inertia
Law stating objects at rest tend to stay at rest, and objects in motion tend to stay in motion, unless acted upon by a net external force.
Newton's 2nd Law-
Force equals mass times acceleration. It takes a force to speed up a mass. The force used in this equation is net (sum of all forces)
Newton's 3rd Law- Action/Reaction
Forces come in pairs they that are equal and opposite in direction. Or, for every action, there is an equal and opposite reaction. These forces don't cancel out because they are on two different objects.
friction
the force that opposes (is opposite of) the motion of one surface as it moves across another surface. It can never be bigger than the force causing movement.
mass
the amount of matter in an object.. Standard SI unit is kilograms i
Newton
A unit of measure that equals the force required to accelerate 1 kilogram of mass at 1 meter per second per second
momentum
a property of a moving object that depends on the objects mass and velocity and is calculated using momentum= m x v. Momentum is conserved and can be transferred from one object to another.
displacement
Distance and direction of an object's change in position from the starting point. It can be calculated by using the Pythagorean theorem.
force diagram
A diagram used to visually keep track of all the forces acting on an object; arrows show the magnitude of the force and the direction. Common forces are applied, friction, weight and normal. Fa, Ff, Fg and Fn
balanced forces
Equal forces acting on an object in opposite directions. No change in motion will happen.
Use F=MA
a 10kg mass is accelerated 5m/s/s. What is its force?
Calculate average speed or velocity
a bus goes 50km/hr for 1 hr and 60km/hr for 2 hours. Total distance divided by total time is (50+120)/3
Unbalanced Forces
These forces cause a change in movement and net force is greater than zero.
Net Forces
Add forces in the positive direction and subtract those in the negative direction. Use this Force to calculate the acceleration a=F/m
Weight
is a force due to the pull of gravity on a mass. To find weight multiply mass by 10m/s2