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We learned about actual mechanical advantage (AMA) and ideological mechanical advantage (IMA). The actual mechanical advantage is the ratio of output force to input force of a machine. It is represented by by output force / input force. IMA is the ratio of output distance to input distance of a machine. It is represented by the formula D in / D out. AMA/IMA is equal to the efficiency. By definition efficiency of a machine is the ratio of useful energy output to the total energy output.

Today in class we learned about machines. A machine is anything that is used for increasing a force or changing the direction of the force. In a perfect system the work put in is equal to the equal to the work put out. We know that no machine can produce the same exact work as an output then we put in. The three machines that everything is based off of are the pulley, lever, and incline.

nickragone-blog

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nickragone:

In the the string and the pulleys may have been the reason for which we got efficiency calculations over 100%. One of the reasons could have been because of the elasticity of the string and that we measured the effort distance wrong.

Geez, look at this tank! This is our setup for the Pulley System efficiency lab. We used many materials for this lab including, a weight, a newton scale, and double and single pulley.

This is a picture of Nick playing the guitar with the meter stick. Today in the lab we measured the effort and the effort distance. The resistance or the weight of the object remained constant as did the resistance distance (at 10 cm). We used the numbers to calculate the AMA, IMA and efficiency. This was done so with a double pulley, and single pulley, some string, a weight, and a force scale.

A roller coaster is a perfect example of the law of conservation of energy. The height times the mass of cars times gravity gives the potential energy before the ride starts, which is the entire energy of the system. On the ride the energy is not gained or lost(unless acted on by outside forces) but is just transformed between potential and kinetic energy. If at the end of the ride, the roller coaster cant achieve its original height, it can be concluded that energy was lost along the ride.

Today in class we learned about mechanical energy. We learned that mechanical energy is the sum of the kinetic and the potential energy of the system. The law of conservation of energy says that energy cannot be created or destroyed it can only change from one form to another, but while it is changing the magnitude of the energy will never change. In a system the sum of PE and KE will always equal the same amount. At different points in the system there will be a different about of kinetic or potential energy but the sum will remain the same.

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Mechanical Energy

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nickragone:

This is also means that in a closed potential and kinetic energy system the amount of energy is always conserved. When the object is not moving all the energy is going to be potential. When it is at the floor all of the energy is going to be kinetic. When it is moving at a height it is going to be both kinetic and potential. When we have thee totals of energy we can find the speed of the object.

The mechanical energy of a system is equal to Kinetic Energy + Potential Energy. When this mechanical energy is conserved, the energy that is present before the event is equal to the energy present after. PEg = mgh KE = 1/2mv^2

Potential Energy

On Monday we learned about potential energy. Potential energy is the energy of the position. It must refer to the relative position of two objects. We also learned about PEg. This is the work require to elevate the object against gravity. The PEg is also equal to work which means that it must also be equal to F x D. The equation for PEg is mxgxh where m=the mass, g=the gravity, and h=the height of the object.

Today in class we learned about power. By definition, power is the rate at which work is done or energy is transformed. The equation for power (represented by the letter P) is the work done, divided by the time. Power is how fast the work is done. Power is also expressed in forms of watts and horsepower. One horsepower is equal to .7 kilowatts or 700 watts. All forms of energy are expressed in the SI unit known as the Joule (J).

srizz29-blog

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srizz29:

To start off, based on the video its pretty clear that I was timed wrong and i was much faster. To calculate the power in Ft Lbs/S you have to multiply my weight times the distance and divided it by the falsely recorded 4.7 seconds. For the horsepower you divide that answer by 550. And then finally to find out the wattage you divide the Ft Lbs/S by 0.738

This is Tyler running up 16.3 feet of stairs. By timing him and measuring the distance he ran we were able to then calculate his power, horsepower, and watts. Tyler’s time is not that fast, but we are not here to judge- just calculate.

Lab

On Wednesday we did a lab on finding power production. After we measured the height of the a step, and multiplied it by the number of steps we each did a run up the steps and recorded the times. After we got back to the lab we all weighed ourselves in newtons. Then we took that number and divided it by 4.45 to get the weight in pounds. We multiplied this weight by the distance and then divided by the time to get the Foot Pounds per Second(Ft Lbs/S). This number divided by 550 gave the amount of horsepower each person had. Finally we took Ft Lbs/S and divided it by .738 to find the amount of watts each person generated.

Today we learned about work. Work only occurs on an object that is moving. By definition, work is the product of the force on an object and the distance it is moved. It is represented by the equation, W=FD. The unit of work is the Joule (J) which is also known as the Newton Meter. There are two types of work. The first is work done against another force. The second type of work is done to change the velocity of something.

During a collision, after the two objects collide, their is a transfer of momentum. The equation for momentum is p=mv. The object with the greater momentum before the collision, in other words the heavier object that is moving faster, will transfer more momentum to the smaller and slower object will to it. In a real life example, the concept is seen while playing pool. The ball moving faster runs into the sedentary ball and the attacking ball slows down, losing some of its momentum. On the other hand the momentum is transferred to the ball that is moving and it begins to move faster.

canyoubelievethisurlwasavai-blog

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canyoubelievethisurlwasavailable:

This is very true. Impulse can also be set equal to change in V times M because that is the formula for change in momentum, which is essentially the definition of impulse. Also how do you get a change in sign on tumblr like that?

Impulse is a vector. It can be defined as the force acting on an object times the time during which the force is exerted. The equation is J(impulse)=f▲t. Either parts of the previous equation can be set equal to ▲p(momentum). Because of this, a small force...

This week we learned about impulse. Impulse is also known as the change in momentum symbolized by change in p. The impulse of the first object in a collision is equal to the impulse of the second object involved in the collision. In other words the change in momentum in which the first object experienced was the same as the change momentum of the second object. Because of this, this means that impulse is also equal to the change in velocity times the mass because that is the formula for change in momentum

Today in class we learned about impulse. Impulse is greater when things bounce off of each other, or another way of saying that is in an elastic collision. In an elastic collision impulse is needed to bring the object to a stop, and then to throw it back again. For example when a tennis ball is thrown at the wall, impulse is exerted when to get the ball to come to a complete stop, and then is exerted to get the ball to come back off of the wall. The symbol letter for impulse is J and the equation for it is J=FT.

As I was driving home from SAT class I passed a car crash. When I saw the damage in which each car had, it made me think about the type of the collision that had ensued. I considered the factors. The fact that the cars had bounced off each other, and the fact that they had continued with an amount of energy after the collision led me to believe that it was elastic. I then thought that energy must have been lost since the cars' velocities decreased, so it had to be inelastic. But due to the fact that an outside force, the breaks of each car, played a role in the collision, I came to the conclusion that the collision was elastic.

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