Chapter 2: Work snd Energy Flashcards
Kinetic energy equation
Gravitational potential energy
the energy stored in an object due to its position above the earths surface
Elastic potential energy
Total mechanical energy
E = U + K
= potential energy + kinetic energy
(mechanical) work equation
work done by nonconservative forces equation:
U =
K =
what is a Pulley
a wheel with a grooved rim around which a cord passes
they are used to change the direction and/or magnitude of force required to lift the suspended object
two types of pulleys
fixed
load sharing (moveable)
Do fixed pulleys offer mechanical advantage?
NO.
If you have a 1lb weight hanging from a fixed pulley, you will need to pull down on the rope with 1lb of force
How much will an object on a fixed pulley raise if you pull the rope down 1 meter?
1 meter
the movement of the weight is directly proportional to the pull distance
What is the purpose of a fixed pulley
changes the DIRECTION of force required
load sharing pulleys (increase/decrease) the force required and (increase/decrease) the pull distance required
load sharing pulleys decrease the force required and increase the pull distance required
mechanical advantage
MA = force out / force in
the mechanical advantage of a pulley system is related to …
the number of load sharing pulleys present
the “force out” in mechanical advantage is …
the weight of the load
adding 1 movable pulley will decrease the force required by a factor of –
TWO
b/c each side of the rope carries half the weight
the mechanical advantage of a pulley system is equal to …
the number of ropes supporting the moveable pulleys
