Energy Handout

II. Energy (Joules) - 2 kinds

A) Potential Energy - ____________ energy of that an object has due to its

____________ or _____________________.

1. Gravitational P.E. _g (PE is an abbreviation for Potential

Energy)

P.E. _g = _______________________________ g - on earth = ____________

units

DP.E. = ____________

Ex 1 ) What P.E. is gained when a 100kg object when it is raised 4m straight up?

DPE = mgDh

Ex 1a ) What PE would be gain if the object were moved 4m to the right? _______________

2. Elastic P.E. - work stored in a deformed spring

a) General Equation PE _s = F × x

F = Average F needed to deform spring x = distance deformed

b) Hookes law - _____________needed to deform an ideal spring, a

given amount is directly proportional to its __________________

Example) Ideal Spring X

F (force to deform) X (distance deformed)

2N .3m

4N ____

6N ____

8N ____

Force (N)

Stretch (m) slope = F/X

c) Spring constant for ideal Spring X

K = F/X =

d) Elastic P.E. = area of triangle under F vs x graph

PE s =

e) PE_s in terms of k

1. P.E._s = __________ Average Force: ________

2. PE = ____________ F = Kx (On reference)

3. P.E._s = _______________ (On reference)

Ex1) A force of 12 N stretches a spring and makes it .15m longer.

a) What the spring constant (k) of this spring?

b) What's the potential energy of this spring?

B) Kinetic Energy - the energy an object possesses due to its _______________

Work/Energy Relationship: The kinetic energy an object possesses is equal to the

____________________ done to get an object moving a certain speed or to stop it.

Equation….. K E = ______________________

Relationships: K E / m _______________ KE/ v ________________