Formula of Conservation of Energy
Ei=Ef
EKi+Ugi+Usi=EKf+Ugf+Usf+EHf
Definition
Ei=Ef
EKi+Ugi+Usi=EKf+Ugf+Usf+EHf
Definition
Energy cannot be neither created or destroyed;
it can only be transformed from one form to another.
The total amount of energy remains constant.
Units of Energy
Units of Energy
SI units:
- Joule (J)
- Joule (J)
American Units:
-
Calories (Cal)
-
British thermal unit (BTU)
American Units:
- Calories (Cal)
- British thermal unit (BTU)
Video Link
This video shows us how the law of conservation of energy is being applied into a circus acts.
When the performer is at rest on the bar its showing us her Kinetic Energy is at zero.
As she jumps on the bar her Kinetic Energy turns into Elastic Energy.
As shes getting high her Kinetic Energy becomes Gravitational Potential Energy.
This video shows us how the law of conservation of energy is being applied into a circus acts.
When the performer is at rest on the bar its showing us her Kinetic Energy is at zero.
As she jumps on the bar her Kinetic Energy turns into Elastic Energy.
As she jumps on the bar her Kinetic Energy turns into Elastic Energy.
As shes getting high her Kinetic Energy becomes Gravitational Potential Energy.
Example Problem
Use the law of conservation of energy (assume no friction)
Example Problem
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.
to fill in the blanks at the various marked positions for a 1000-kg roller coaster car.
A: h = 45.9 m (from 450 000 =1000*9.8*h)
B: v = 0 m/s (since KE = 0 J)
C: KE = 250 000 J (KE + PE must equal 450 000 J)
D: h = 20.4 m (From 200 000 =1000*9.8*h)
E: v = 22.4 m/s (from 250 000 = 0.5*1000*v^2)
F: KE = 450 000 J (KE + PE must equal 450 000 J)
G: PE = 0 J (since the height is 0 m)
H: v = 31.6 m/s (from 500 000 = 0.5*1000*v^2)
I: a = 7.07 m/s/s (since a = g*sin angle)
X - Games Loop
The Potential energy is stored at the very top of the loop.
Velocity = 0 m/s
Potential energy is keeping him at the very top of the loop, while gravity is trying to push him down.
mgh1 = mgh2 + mv^2 / 2
gh1 - gh2 = (v^2) / 2
(9.8) (7) - (9.8) (4.5) = (v^2) / 2
68.6 - 44.1 = (v^2) / 2
2 (24.5) = ((v^2) / 2) 2
√(49) = √(v^2)
7 m/s = v
The Kinetic energy is the fastest when all the stored energy is about to go around the loop.
mvi / 2 + mgh1 = mgh2 + mvf^2 / 2
mgh1 = mvf^2 / 2
gh1 = vf^2 / 2
(9.8) (7) = vf^2 / 2
(68.6) 2 = (vf^2 / 2) 2
137.2= vf^2
√137.2 = vf
11.71 m/s= vf
X - Games Loop
 |
| The Potential energy is stored at the very top of the loop. Velocity = 0 m/s |
 |
| Potential energy is keeping him at the very top of the loop, while gravity is trying to push him down.
mgh1 = mgh2 + mv^2 / 2
gh1 - gh2 = (v^2) / 2
(9.8) (7) - (9.8) (4.5) = (v^2) / 2
68.6 - 44.1 = (v^2) / 2
2 (24.5) = ((v^2) / 2) 2
√(49) = √(v^2)
7 m/s = v
|
 |
| The Kinetic energy is the fastest when all the stored energy is about to go around the loop.
mvi / 2 + mgh1 = mgh2 + mvf^2 / 2
mgh1 = mvf^2 / 2
gh1 = vf^2 / 2
(9.8) (7) = vf^2 / 2
(68.6) 2 = (vf^2 / 2) 2
137.2= vf^2
√137.2 = vf
11.71 m/s= vf
|
