Blog #5

Solar panels make sense for a primary usable energy source because we will always have the sun unless it is night time, all day long while the sun is shinning on the solar panels it is creating energy. Different temperatures during the day, creating heat(energy) apply the 2nd law of thermodynamics. The changing of temperatures will cause a form of energy to be created.



1. Sally does 210J of work lifting herself 5.5 m with a gravity pull of 9.8
What is Sally's mass?

Us=(1/2)kx^2
x=5.5
Us=?
F=210

(210)(5.5)= 1155


2. What is the definition of Us?

(a)the energy stored in a compressed or stretched spring
(b)the energy of motion for an object
(c)a measure of stiffness of a spring

answer: a

3.  What is the variable, definition and unit of power?
-variable: P
-definition: the rate at which energy is used
-unit: Watts(w)

Blog #4

An activity I do that uses energy is wake boarding. You need to use kinetic energy to get yourself up out of the water and ride the wake back and forth. Once you get up out of the water the boat mostly pulls you, unless you want to do tricks or jump the wake, you still use kinetic energy by increasing the amount of work you do. The energy consumption dies down when you let go of the rope and your body stops moving or using energy.

Wake Boarding

1.  An object initially at rest is pushed with a force of 76N and a distance of 12m. What is the change in kinetic energy as result of the force?
equation: Uw=Ukf-Uki
x=12
F=76
Uki=0
Uw=Uk
76(12)= 912

2. An object has the most potential energy when..
(a) it is at the lowest of its travel
(b)  it is at its highest point
(c) it hasn't even started to move

answer: B

3. Calculate the kinetic energy of an object 24kg object moving at 45m/s
Uk=(1/2)mv^2
m = 24kg
v= 45m/s
Uk=?
Uk=(1/2)(24)(45^2)
Uk= 24300

4. The more displacement the ______ work. The more force the ________ work.

Blog #3

Nuclear power

• used as a bomb
• powerful

Hydrogen fuel

• fuel made with oxygen and water
• used to make some machines work, its probably more environmental friendly

Coal

• produces heat and energy

Oil

• used in the 19th century to opperate machinary 
• need to create fuel

Living Green

• Solar energy
• using natural resources to make things work or used a fuel
• living to better the environment without creating to much pollution

Energy Efficiency 

• the amount of energy that is used
• using energy when needed and not abusing it

If you have a force of 26N to move a weight .85m. How much work do you do?
 equation: Uw=Fcos(angle)deltax
                                                    
F: 26N                                                     
d: .85m
angle:0
Uw=26cos(0).85
Uw= 22.1J 

A bicycle traveling initially at 7.56 m?s accelerates at the rate of .843 m/s^2 for 3.21s. What is its velocity at the end of the acceleration?
equation: vf= vi+at
vf: ?
vi: 7.56
a= .843
t= 3.21
vf= 7.56+ (.843)(3.21)
vf:10.26603

One watt if equivilant to how many joules?  
3,600,000