#### Transcript PHYSICS

```Gravitational Potential Energy
 Can

do positive or negative work.
• mg is the only force acting on the basketball.
s
• The initial height of the basketball is ho
• The final height of the ball is hf
• The displacement of the ball is s
 To
mg
hO
Calculate Work
• W=(Fcos0)s with F = mg and 0 = 0°
• Wgravity = mg(ho – hf)
hf
mg
 PE
= mgh
 Units of GPE is joule (J)
 Work
being done is equal to PE final – PE
initial.
 Gravitational Potential Energy, like work
and Kinetic Energy is scalar.
 Conservative
Forces:
• A force is conservative when the work it does on
a moving object is independent of the path
between the object’s initial and final positions.
• A force is conservative when it does no net work
on an object moving around a closed path,
starting and finishing at the same point.
• Work done by gravity depends only on the initial
and final heights, and not the path between
these heights.
 Nonconservative:
• A forces is nonconservative if the work it does on
an object moving between two points depends
on the path of the motion between the two
points.
 An
object can possess two kinds of
energy: Kinetic energy and gravitational
potential energy.
 The sum of KE and PE is called total
mechanical energy.
 Wnc
= (KEf-KEi) + (PEf – PEi)
 The
total mechanical energy (E=KE + PE)
of an object remains constant as the
object moves, provided that the net wor
done by external nonconservative forces
is zero.
Kinetic Energy
Potential
Energy
Total
Mechanical
Energy
0J
600000 J
600000 J
200000 J
400000 J
600000 J
400000 J
200000 J
600000 J
600000 J
0J
600000 J
 LAB:
 Energy in Simple Harmonic
• Preliminary Questions:
Motion
 Write them out and then answer.
• Procedure:
 Describe what you did as detailed as possible.
• Data:
• Analysis Questions:
 Write them out and then answer
```