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44 Cards in this Set
- Front
- Back
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formula for pressure
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Pressure = force (F) (Newtons)/area (a) (sq meters)
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another way to calculate the mechanical advantage of a pulley
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Count the # of ropes supporting the load (except for the rope the person pulls on, IF its connected to a FIXED pulley) IF that rope comes from a moveable pulley it should be counted
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the effort required to move a load is
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load force/appropriate # of pulleys
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mechanical advantage (MA) of moveable pulley
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MA=length of rope pulled by effort/displacement of load
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MA for fixed pulley
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MA=1
To raise a 100lb load, must exert a 100lb force |
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MA of lever
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MA=load force/effort force
MA=displacement of load/displacement of effort |
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How can you reduce the effort required when using a lever
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if effort is made at a greater distance away from pivot pt (the closer, the more effort)
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MA of inclined plane (ramp)
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1. find ramp length
ramp length= sqrt(ramp distance^2) + (vertical rise^2) 2.MA=the length of ramp/vertical change |
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the length of a ramp is
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the hypotnuse of a triangle
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equation to calculate work
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W=F(force) x d(displacement)
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equation for mechanical advantage (MA)
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MA=load force/effort force
MA= distance over which effort applier moves/distance over which load moves |
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equation for weight
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weight=mass x the acceleration due to gravity
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acceleration due to gravity =
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9.8m/s^2
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buoyant force
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the buoyant force acting on an object that is partially or fully submerged is EQUAL to the weight of the fluid that is displaced
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pressure
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P=D x g x h
P= Density x acceleration of gravity x depth of liquid |
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How do you find the distance traveled from start to finish in a grid
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count the unit squares along the path
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Newtons 3rd law
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for every action there is an equal and opposite reaction
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Example of newtons 3rd law
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when you throw a ball, the ball moves forward and you move back. you exert force on the ball and the ball exerts force on you
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friction
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surfaces that touch each other have a certain resistence to motion. this resistence is friction
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the direction of the frictional force is ________ to the direction of the motion
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opposite
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a force that is equal to the weight of the object and points up
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buoyant force
ex: pool toy |
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compression
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the result of a force applied to the outside of an object that pushes inward or acts to reduce the size or volume of an object
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compression equation
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force applied: Y= (Delta L)/(Lo)
Lo=original length of object Delta L= change in length when force is applied |
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tension force
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the force of a rope or string that is pulling on an object
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In TENSION FORCE the direction of the force is always ______ from the surface of the object to which the rope is attached
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away
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in tension force the length of the rope is constand and tension is _______ everywhere
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equal
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normal force
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acts perpendicularly out from the surface of the object that is exerting it
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example of normal force
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book lying on table: the book is exerting a downward force on the table, equal to the weight of the book. BUT the NORMAL force is the force exerted by the table on the book, pointing up
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the normal force points _______ from the surface no matter how the surface is inclined
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away
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four fundamental forces in nature
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gravity, electromagnetic, strong nuclear forces, weak nuclear forces
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Newtons 2nd law
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If a net force acts on an object, it will cause the acceleration of an object
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the relationship between force and motion is
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F=MA
Force=mass x acceleration |
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mass =
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mass = force/acceleration
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Newtons 1st law
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the law of inertia
an object in motion will remain in motion at a constant velocity unless acted upon by an external force |
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what is the net force of an object
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net force of an object is always EQUAL to the objects mass x acceleration
(m x a) |
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an unbalanced force is
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net force
-unbalanced forces cause changes in velocity |
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equation for acceleration
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change in velocity/time interval when change occured
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acceleration
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change in velocity
-slowing down -speeding up -changing direction |
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how do we measure uniform and nonuniform motion
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uniform motion: dots equally space, neither speeding up or slowing down
nonuniform motion: spacing in dots varies -closer together=slowing down -farther apart=speeding up |
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velocity
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the rate of change in position(vector) per unit time
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speed
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how fast something is moving
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how do we describe an objects motion
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recording the change in position of the object over time
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magnitude
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the length of a vector
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symbol for displacement
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d or Delta s
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