unit 4 Flashcards
work
force applied through a distance
the direction of the force that you apply to an object affects how much ___ you do on it
work
when ____ + _____ are parallel, w=fd
force, motion
when force is _____ to motion, the work from that force is ____
perpendicular, 0
you can only do ____ on an object while applying ____ on an object
work, force
device that changes the force/increases the motion from work
machine
machine that does work with only 1 movement of the machine
simple machine
examples of a simple machine
lever, pulley, wheel and axle, inclined plane, screw, wedge
combination of 2 plus simple machines
compound machine
examples of compound machine
scissors, bicycle
machines can increase for ____ increase speed
or
the ratio of output work to input work
efficiency
what is efficiency measured in
%
efficiency equation
e = w out/w in x 100
how are machines made effeicient?
reducing friction (adding lubricant- oil/grease)
ratio of the output force to input force
mechanical advantage
mechanical advantage equation
MA = Fout/ Fin
force that a person/ device applies to a machine
input force
force that the machinr applies to another object
output force
the ability to cause change
energy
what can energy be described as?
the ability to do work
what is energy measured in?
joules
anything around which you can imagine a boundary
system
a system can be ____ or a _____ of objects
single; group
true or false:
when 1 system does work on a 2 system, energy is transferred from one sytem to the second system
true
what are the different forms of energy?
mechanical
chemical
radiant
electrical
energy due to motion
kinetic energy
what type of energy depends on objects mass and speed
kinetic energy
kinetic energy equation
KE = 1/2 mv^2
energy stored due to interactions between objects
potential energy
energy stored by compressing or stretching an object
elastic potential energy
energy due to chemical bonds
chemical potential energy
energy due to the gravitational forces between objects
gravitaional potential energy
the GPE of a system with just earth and the object depends on objects ___, earths ____ and object ____
mass, gravity, height
near earths surface, g = _____
9.8 n/kg
GPE equation
GPE = mgh
GPE varies with chosen ____
refence level
law of conservation of energy
energy cannot be created or destroyed
true or false:
energy cannot convert from 1 form to another and cannot transfer 1 place to another
false; can
the universal principle states that the _____ ______ remains a constant
total energy
the sum of the kinetic and potential energy of the objects in a system
mechanical energy
mechanical energy examples
kinetic, elastic, potential, gravitational potential energy
energy transformations happen during _____ _____ when an object moves in a curved path
projectile motion
what type of energy does fraction and air resistance convert some mechanical energy to?
thermal energy
what type of energy does feul store ?
chemical potential energy
the rate at which energy is converted
power
power equation
P = e/t
energy/time
power is measured in what?
watts
1 watt = 1 ____ per second
joule
energy from food is measured in ____
calories
every gram of foos fat = how many calories of energy?
10
carbs and proteins each = how many calories of energy per gram?
5
everythinng out body does needs what?
energy
radiant energy comes from what type of energy
electrical energy
when an object is in freefall, kinetic energy _____, while GPE _____
increases; decreaases
what energy comes from food?
chemical enegry
law of consevrtaion of enegry means that the toatl energy remains ____
constant
