In this unit, I learned.....
WORK AND POWER
when a force moves something through a distance, work is done.
Work= force x distance
Work is measured in joules.
When is work present?
Work is present when both the force and distance are parallel. When grocery shopping, both your distance and force are parallel when pushing a cart, therefore work is being done.
Also, when this boy pushes a sled, work is being done because force and distance are parallel.
WHERE IT GETS TRICKY
Stairs....
Stairs can be confusing. If you are going up stairs you DO have work, however, the confusing aspect is what distance you use, as there is a horizontal and vertical distance. YOU USE THE VERTICAL DISTANCE.
Let's try this out
I need to go to second mitchell. In which case will I use more work, the stairs or the elevator?
Answer: I will use the same amount of work in both cases because I will have the same force as well as travel the same distance.
Is work present in this? ^^^
Answer: No, there is no work because the force and distance are not parallel. While the distance is horizontal, the force is vertical. Also, there is no work on the tray because it is moving.
Also, if someone is pushing something and it does not move, no work is done.
POWER
power is how quickly work is done.
power=work/time
power is measured in watts
1 Horsepower=746 watts
Light bulbs
So, 100watt light bulb will generate more power therefore do work faster than a 60 watt lightbulb.
WORK AND KINETIC ENERGY RELATIONS
Where did work come from?
Mass & speed have the ability to do work
movement fuels energy
SO....
Kinetic Energy=1/2mv^2
change in kinetic energy=KE(final)-KE(initial)
kinetic energy is basically energy something has when moving
This polar bear is generating kinetic energy because it has a velocity and mass, and as it moves, this is being applied into kinetic energy.
does he have kinetic energy?
he does not have kinetic energy because he does not have a velocity. If something does not have a velocity, it cannot have kinetic energy.
CONSERVATION OF ENERGY
key question:
Why do airbags keep us safe?
1) When we are riding in a car, we are moving, therefore doing work.
2) kinetic energy=1/2mv^2
3) change in kinetic energy=KEfinal-KEinitial
4) change in kinetic energy=work
5) work=force x distance
6) the airbags increase the distance therefore the force is less. conservation of energy: work with airbag=work with dash
POTENTIAL ENERGY
Potential energy=potential energy is the energy of position. Movement can be transformed into kinetic energy.
when you throw something up, because of the force of gravity, the higher you get up, the less kinetic energy you will have as it will be converted to potential energy
when kinetic energy goes up potential energy goes down and vice versa
PE=mgh
so how do roller coasters work?
roller coasters are able to function because they store up potential energy then it is converted into kinetic and then back to potential, then back to kinetic, and so on. The law of conservation of energy.
INCLINED PLANES/MACHINES
we use ramps to ultimately reduce the amount of force it takes to get somewhere, when you increase the distance, the force is less. That is what ramps do.
machines also reduce the amount of force and increase distance
For pulleys, tension on each side is equal.
SCISSORS
the long handle and short blade allow scissors to cut with more force
EFFICIENCY=workout/workin
the work out can never be more than the work in
WHAT I FOUND MOST DIFFICULT
This unit was definitely difficult. I struggled in a lot of areas, particularly the machine section. However, I got over these difficulties through conference period and looking at other peoples blogs. The light bulb clicked when doing so.
My problem solving skills got better....
Obviously, the more we solve problems, the better we will get at them. Therefore, the more problems I do, the better I will get at them. Through doing take home quizzes, I was able to really sit down and work things out slowly, therefore understand problems better. Through this process, I was able to improve my problem solving skills.
My goals for next unit is to do better on quizzes, because I recently scored poorly on the latest quiz. In order to do this, I need to work harder to seek extra help when I need it.
REAL LIFE? Real life connections are present throughout my explanations.
MY PODCAST WILL NOT EMBED SO HERE IS A LINK!
http://www.youtube.com/watch?v=zEGO1eI-SNg
This unit was definitely difficult. I struggled in a lot of areas, particularly the machine section. However, I got over these difficulties through conference period and looking at other peoples blogs. The light bulb clicked when doing so.
My problem solving skills got better....
Obviously, the more we solve problems, the better we will get at them. Therefore, the more problems I do, the better I will get at them. Through doing take home quizzes, I was able to really sit down and work things out slowly, therefore understand problems better. Through this process, I was able to improve my problem solving skills.
My goals for next unit is to do better on quizzes, because I recently scored poorly on the latest quiz. In order to do this, I need to work harder to seek extra help when I need it.
REAL LIFE? Real life connections are present throughout my explanations.
MY PODCAST WILL NOT EMBED SO HERE IS A LINK!
