Chapter 2: Work snd Energy Flashcards
(20 cards)
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
How much will an object on a moveable pulley raise if you pull the rope down 1 meter?
half a meter
Mechanical advantage of a system with 1 movable pulley
2
the mechanical advantage of a pulley system is equal to …
the number of ropes supporting the moveable pulleys
