Conservation of Energy

Conservation of Energy

CONSERVATION 

OF
ENERGY

CONSERVATION OF                                                          Abbreviated Version:                              ENERGY:   Energy that cannot be destroyed or created,       KEi + PEi = KEf + PEf 

but can adjusted from one form to another or transferred       Extended Version: 
from one subject to another.                                                  1/2mv^2i+mgh=1/2mv^2f+mghf


Different units of energy:
a. SI units are measured The ampere is the SI base unit of electrical current, The candela is the SI base unit of luminous intensity, The kelvin is the SI base unit of thermodynamic temperature.

b. American units are measured in calories, joules, British thermal unit (Btu), and kilowatt- hour (kWh)

                       In this video it explains energy, power and work. The Law of Conservation of Energy states that the total of energy of an isolated system will remain constant and can be conserved over time. This law means that energy can neither means can neither be created or destroyed, it can only transform to one form to another. How energy changes depends on the system. Conservative system does not let you lose energy with work? 

EXAMPLE PROBLEM!!!

1. A ball that weighs 1.8kg has been dropped from the top of a house that is 2.9 meters above the ground. What is the mechanical energy, when speed of the falling ball is 4.8m/s?

KE=1/2mv^2                       GPE=mgh                ME= GPE + KE

1/2 x 1.8 x 4.8^2        1.8 x 10 x 2.9             = 52.2 + 20.7

   = 20.75                        = 52.25                         = 74.95

X - GAMES LOOP

In this photo, the skater is at max height( in the green box). There is no energy being distributed,

potential or kinetic because he is not in motion.

In this photo, there is more potential energy because the skater is at the top of the loop and because he is at the top of  loop, there is less kinetic energy.

In this photo, the skater is at his fastest because there is lots of built of energy that is he got from going down the ramp that is being released, this is kinetic energy. the energy that is gained is potential energy. that's why there is more Kinetic energy than potential energy.

Conservation of Energy Rubric

Conservation of Energy

Conservation of Energy Rubric

Mr. Dehn's 1st Period Physics Class-Blog

Passing The Class

Passing This Class

The Law of Conservation of Energy

The Law of Conservation of Energy

Mr. Dehn's Period 1 Physics Class

Conservation of Energy

Conservation of Energy

Conservation of Energy

conservation of energy

The Law of Conservation of Energy

Mr. Dehn's 1st Period Physics Class

Law of Conservation of Energy:

• The law of conservation of energy is that energy cannot be created nor destroyed it can only be transferred and stored in other objects.

Mathematical representation of the law of conservation of energy:

1. Abbreviated version: Ei=Ef
2. Extended Version: GPEi+SPEi+KEi+PGEf+SPEf+KEf

Units of Energy:

1. SI units: Joules
2. American Units:  Calories and BTU

Video and Explanation:

a.

b.Energy is conserved in a roller coaster as shown in the video, it carries a
relationship between both potential and kinetic energy. The roller coaster has both
potential and kinetic energy because when the roller coaster goes up it has potential
energy and when it travels down it has kinetic energy. When the roller coaster goes
at the top of the loop it uses gravitational energy to go down. The conservation of
energy is traded off between both types of energies.

Problems:

1. Use the law of conservation of energy (assume no friction) to fill in the blanks at the various marked positions for a 1000-kg roller coaster car.

   

a.450,000 =1000*9.8*h               

 h=45.9 m 

b. KE=0 J 

 v=0 m/s 

c. KE + PE =450,000 J

 KE = 250,000 J

 d.  200,000=1000*9.8*h 

 h = 20.4 m 

e. 250,000=0.5*1000*v^2

v=22.4 m/s 

f. KE+PE=450,000 J

 KE=450 000 J 

g. the height is 0 m

PE = 0 J 

h. 500,000=0.5*1000*v^2 

v = 31.6 m/s 

i. a=g*sin angle

a = 7.07 m/s/s

2. Brenda is 68 kg, she’s riding her skateboard down a 16 m hill, she is moving at 2 m/s. 
What’s her final velocity?

Known (mvi^2/2)+mghi+(mvf^2/2)+mgh2
M=68 kg (68 x 0)/2+(68 x 9.8 x 16)=(68 x v^2)/2
H=16 m 21,324.8 = (68 x v^2)/2)2
G=9.8 m/s^2 2 x 21,324.8 = (68 x v^2)
Vi=o m/s 42,649.6 =(68 x v^2)
Unknown 42,649.6 /68=v^2
Vf=?                    25.04=vf
                                                         

X-games loop:

There is only potential energy because no movement has occurred yet which means that the energy is stored.
0 m/s because its at rest.

There is more potential energy than kinetic because there's nothing but gravity pulling the skater down.         

mgh1=mgh2 + mv^2 / 2 →gh1-gh2=(v^2) / 2→(9.8) (8) - (9.8) (3.5) = (v^2) / 2→78.4 - 34.3 = (v^2) / 2→2 (44.1)=(v^2)/2(2)→√88.2)=√(v^2)→v=9.39 m/s  

There more kinetic energy because there's movement since the skater went down the ramp.

                      mvi /2+mgh1=mgh2+mvf^2 / 2 → mgh1 = mvf^2/2 → gh1 = vf^2/2 → (9.8)(8)=vf^2/2 → (78.4)2=(vf^2/2)2 → 156.8=vf^2→ vf=√156.8 →12.52 m/s

Conservation of energy