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

Blog #2

THE GRAVITRON
Description of ride: You enter the spaceship and lay on the inside of its walls it starts to spin and retains a constant velocity. It is spinning so fast it makes you feel heavy, like you are being pushed with such great force that you struggle to move.
NEWTONS LAW OF UNIVERSAL GRAVITATION
NLUG shows that even though the mass of the objects are a mass of heavy or light weight it is not possible for an object to appear to be weightless, even if the masses are the same. The force of gravity is always constant meaning and object will have weight since a force can act upon it. All objects have to have some magnitude of mass in order to have movement or a force that makes it feel weightless or heavy.
ex:
equation: Fg= G(m1)(m2)/d^2
you have two masses & G= universal gravitational constant
m1: .021 kg
m2: .021 kg
G: 6.67 x 10^-11
6.67 x 10^-11(.021)(.021)/(1)^2= 2.94147 x 10^-14
= .0000000000000294147 

Edward has a mass of 59.3kg and Bella has a mass of 52.6kg. Edward and Bella are standing 10.3m apart in a mass-less meadow. Bella looks up and sees Edward. Shes feels and attraction.
If the gravitational constant is 6.67 x 10^-11 find its magnitude in the unit of N.  
equation: Fg= G(m1)(m2)/d^2 D= 10.3
m1= 59.3
m2= 52.6
G= 6.67 x 10^-11

6.67 x 10^-11(59.3)(52.6)/ (10.3)^2
= 1.961064247 x 10^-9
= .000000001961064247

If an object retains a constant speed. Is there a net force on the object as it rounds a curve during its travel?
(a) yes
(b) no
(c) possibly
ans (b) 

What does NLUG stand for and what is the universal gravitation constant?
Newtons law of Universal Gravitation & G= 6.67 x10^-11
 

Blog #1 Part 2

If Fg=Fn and Fa=FA what is the objects possible speed?
a. 179N
b.constant
c. no motion
d. 12kg

Answer b&c
If an object FBD all are equal it is possible that the object could be containing a constant speed or not having any motion at all. When all the forces cancel out it is called an equal librium.

A man is holding four bags of sand from a rope that weight a total of 136N. How much tension is exerted in each strand?

a. 136N

b. 30N

c. 34N

e. none

Answer:  C; 34N 

You take the total weight(N) and then divide it by the number of strings that is holding to find their individual tension.

A box is pulled to the right with a force of 89N, to the left with a force 119N, upward with a force 450N, and downward with a force 139.5N.
What is the net external force in the x direction?
(ans) -30N
The answer must be a negative number because the force is what is making it move that direction. It took more force to move the object in the right direction that it took when the box was actually moving in the right direction.

What is the external force in the y direction?
(ans) 310.5N

Blog #1

Week 7

 In physics the vx= a harmonic motion. At any given point the projectile of vx will always be the same on any point of travel of an object. The amplitude of the distance will always be a constant number just like the vx will always remain constant. The amplitude could be better described as the maximun displacment of the highest point on the oscillation. The horses on a carousel are a good example of harmonic motion. They all move together at a constant speed and the same distance. The vx is always the same when you take its absolute value. It doesn't matter at what  point the object us in its time of travel the vx will ALWAYS be the same, the only factors that will change are the vy and v.

vx= velocity in x direction
vy= velocity in y direction
v= velocity

A bottle rocket is launched from the ground.  The rocket launcher wants to know what the speed of the rocket is going when it hits the ground but he only know the velocity of x when its is in the middle of its travel which is 25 m/s. By looking at the image determine what is the velocity of the x value during its travel includig the time it hits the ground.

Answer: 25 m/s

A soccer ball is kicked with and intial velocity of 20 m/s at an angle of 30 degrees with the horozontal. Determine the time of flight, the horozontal distance.

Answer: The flight time of the ball was 2.04 seconds and the horozontal distance what 35.35

Week 6

A projectile motion in softball occurs after the ball makes contact with the bat. It launches from the bat to some place out on the field. The ball explodes off the bat with a decrasing velocity until it hits the ground and comes to a complete stop. Another example of projectile motion is when someone pushes you and you are standing in a stationary potsition. Your velocity changes from 0 to how ever the amount of force was used by a person to push another.

1. This roller coaster explodes form a intial velocity of 0 to 150 m/s. What is the displacement within 8 seconds of the roller coaster if the roller coaster is moving upward at a 90 degree angle from the ground?

2. An arrow is fired 50 m into the air. How fast is the arrow noving when it reaches its furthest distance it can travel?

0 m/s

3. What is the forlmula for determining the velocity of an object when givin its diameter and time use to travel the average distance?

v= displacement/time

Week 5

Car B going 60 mph off the cliff beacause the engine of the car would be running and would cause the explotion. Car B would also have more velocity and the fall of the crash from the cliff would mean that its fall to the ground would have close velocity to the speed the car was driving. The speed and acceleration that the car is traveling at would result in a harder fall than if it were to just fall from a cliff of run into a wall.



An apple hits the ground after falling from a tree. The distance from the branch to the tree is 4m. What is the amount of time that it takes to fall from the branch to the ground.



A jogger accelerates from rest to a velocity of 37 cm/s. If the displacement of the jogger from where it started to accelerate her acceleration was 25mm. What is the acceleration of the jogger?

(a) Identify the times at which the velocity is 0.

(b) Find the acceleration from 0-25s.

(c) What is the displacement from 0-50s?



Week 4

When walking from point A to point B and retaining a constant speed you don't use acceleration, only velocity. If you are at a constant speed you never use acceleration.  In a situation that you would only use acceleration would be in a 100m dash. You wouldn't want to retain the same speed in a sprint race, you want to continue to get faster and accelerate your speed until you reach the finish line.

1. What indicates the rate of change?
2. What term is used to show a rate in which displacement changes with time?
3. Slope = ?

Week 3

Acceleration is more important when you are running a 200 meter dash. You need to speed up from your initial velocity to your final velocity in order to win the race. The more you can accelerate the better of the chance you have of winning. If you are being timed to run a mile and your coach wants you to have similar speeds every time, velocity is a better. The more consistent you are with having the same speed every lap around the track, the more consistent your mile times are going to be.


1. When finding the area on a graph it determines the what?
2. What are three ways you can accelerate?
3. A constant speed represents?

Week 2

You accelerate for many reasons when you are riding a bike. For instance, if you were about to ride your bike up a steep hill you would have to accelerate by pedaling faster to make it to the top. Another reason you would need to accelerate is if you were riding your bike at the strand along the beach. Usually, there are many people riding on the strand you need to accelerate if there are people behind you trying to get by to get out of their way. If you were in a bike race you would need to accelerate to pass up the person in front of you and win the race.

1. Unlike last week, in this section what does the slope stand for?
2. What is initial velocity?
 3. What is the general meaning of acceleration?

Week 1

Softball is a sport that includes many of the definitions we use in physics. In softball one of the things you use often is speed. You need speed to run the bases, throwing the ball and fielding.  The more speed you have the better chance to have being safe at base and getting the opponents out faster. For a pitcher, the more speed you have coming off the mound the better of a pitcher you are, and the harder it is for the batter to get a hit. We use distance to know how far we need to stand in the outfield or when we chalk the field to prepare for a game. We measure the distances from base to base, making it more accurate. In some games, the scoreboard is used to set a time limit for how long we can play a game. Having the time helps the players know that if they are down runs in a game, they have as certain amount of time to get ahead.


1.  What is another word used for velocity?
2. A change in position is also known as?
3. What is the formula for speed?