Monday, February 23, 2015

Unit 5 Summary

Unit Summary 5
Work and Power
Work is the principle that when applying a force over a distance one uses energy, thus working. To be doing work the distance and the force must be parallel, no work can be done if the distance and the force are not parallel.  Work is measured in Jewels and is a form of energy. The formula is Work=force*distance. No matter how fast the work is done over the same distance the work stays the same. Power is the amount of work done over an amount of time and it is measured in watts. The formula is Power=work/time and 746 watts are equal to 1 horsepower.
Kinetic Energy
Kinetic Energy is the energy that causes something to move and it is measured in Jewels the same as work. The change in Kinetic Energy (KE) is equal to work, the formula is ΔKE=KEinitial-KEfinal and the formula to find Kinetic Energy is KE=1/2mv^2.
Conservation of Energy
The KE is the energy of a moving object, but when the object is not moving it also has energy, Potential Energy (PE). This is the measure of if the object began to move how much KE it would have. When an object is moving it has KE and also PE as these two types of energy transfer back and forth to each other. When an object is at rest it has 0 KE and 1000 PE, once it begins to move it has 800 PE and 200 KE and as the object speeds up the KE increases as well until the KE is 1000 and the PE is 0. There can never be more energy in a system than it starts with, in the case before the PE or KE cannot exceed 1000 because it started with 1000 units of energy, this is stated in the law of conservation of energy where the Energybefore=Energyafter.
Machines 

A machine, like a ramp changes the distribution of energy. Instead of having to lift a box up a meter in one go, one can push the box 4 meters with less force. The ramp increases the distance, but keeps the same amount of work because the box is still being moved up 1 meter, but over a longer horizontal distance. The single burst of energy needed to lift the box that meter is displaced over the distance of 4 meters at a constant or intervened rate. These are labeled work in and work out, the work in is the side with the longer distance while the work out is the side with the shorter distance.

Monday, February 2, 2015

Unit Summary

Rotational and Tangential Velocity
 When something spins it has two velocities a tangential velocity and a rotational velocity. The rotational velocity is how fast the rotation of the object is who many times the object rotates in the allotted time. The inner rotation rotates at the same seep that the outer does. The tangential velocity is the strait velocity, that is the velocity that moves only forward. The inner tangential velocity moves slower than the outer tangential velocity.
Rotational Inertia
The harder it is to spin the more rotational inertia the object has. The axis of rotation is where the object spins and the closer the mass is to the axis the easier it is for the object to spin. As well the farther the mass is from the axis of rotation the harder it is to rotate the object. When it is hard to rotate it has a high rotational inertia and if it is easy to spin it has a small rotational inertia.
Conservation of angular momentum
This is the same principle as the conservation of momentum but with rotating objects. The property states that the momentum before is the same as the momentum after. The formula is P=rotational velocity * rotational inertia. One can regulate the inertia and by consequence the velocity will increase or decrease depending on if you increase the inertia or decrease it.
Torque
Torque is the force that causes things to rotate. Torque is made of a force and a lever arm (T=F*Lever Arm). When an item is balanced the counterclockwise and clockwise torque are equal.
Center of Mass/Gravity
The center of mass/gravity is where the force to an object is applied. As long as the center is over the base of support of the object it will not fall over. The lower the center is the harder it is to tip the object and the wider the base of support the harder it is to tip over.
Centripetal/Centrifugal Force

Centrifugal force is made up, it does not exist. The only force acting is the centripetal force which is the force that pulls objects into the center. This force can be the combination of gravity and tension or support, or a wall pushing the object to the center.