Euler's disk

II. Energy (Joules)

- 2 kinds

Potential & Kinetic Energy

A) Potential Energy - stored energy that an object has due to its position or condition.

At what position(s) or condition(s)
do these objects have the most PE?

1. Gravitational P.E._g

(PE = Potential Energy)

P.E._g=	(mg)h =	(weight)h
Joules	Kg (m/s²)m	N m
		(Not in reference)

g on earth = 9.8 m/s²

mg = weight

(force it could exert)

h = height

(distance force could be exerted)

ΔP.E.	= mgΔh	= wΔh
		(Not in reference)

Ex 1) What P.E. is gained when a 100. kg object is raised 4.00 m straight up?

m = 100. kg

h = 4.00 m

ΔP.E. = mgΔh

= (100. kg)(9.81 m/s²)4.00 m

= 3920 J

Ex 2) What PE would be gained if an object were moved 4 m to the right?

ΔP.E. = 0

Ex 3) An object weighing 15. N is lifted from the ground to a height of 0.22 m. Find object's change in PE

ΔP.E.	= mgΔh	= wΔh
		*(Not in reference)*

w = 15. N

h = .22 m

ΔP.E. = wΔh

ΔP.E. = 15. N(.22m)

ΔP.E. = 3.3 Nm

Crow bars reduce the force needed
to move a body

G. P. Quackenbos A.M. A Natural Philosophy: Embracing the Most Recent Discoveries in the Various Branches of Physics, and Exhibiting the Application of Scientific Principles in Every-day Life (New York: D. Appleton and Company, 1859) 95

Clipart ETC

... remember what you learned on a seesaw?

Clipart ETC

Elastic PE