# We Must

One vital concept of physics is the energy. The universe possesses energy and matter. For simplicity, matter is a substance and energy is used to move these substances. Energy is appearing in various forms. Among those are kinetic, gravitational potential, elastic potential, electric potential, thermal, chemical, etc. Work, on the other hand, is the change in energy from one form to another by means of an external force. When work is done on an object, therefore, the object is said to have either gained or lost a certain amount of energy of a particular type. The total work done on a particle by all forces that act on it is equal to the change in its kinetic energy, also known as the work-energy theorem.

This can derived from:

W=Fdx equation 1

W=maxdx where ax=vdvdx

W=mvdvdxdx=mvdv

W=v1v2mvdv

=12mv22-12mv12

=K2-K1

W=ΔK equation 2

For a body moving along s , displacement with a constant force F, work can be defined as: W= F . s equation 3

The SI unit for work is J, Joule which is equal to 0.7376 ft.lb in British System. For instance that F is not parallel to displacement, only the component parallel to the displacement can only affect work. The angle θ between F and s, is related by: W=Fscosθ equation 4

When force is in the same direction with displacement which is the maximum, work is simply: W=Fs equation 5

It is related to the magnitude of the vector dot product of force and displacement. Thus, by analysis, for angle θ is 900, force is perpendicular to displacement. Therefore, W=Fscos(900)=0. On the other hand, Power, which is another term in physics, is the rate of time at which work is done. Power is a function of time unlike in work which is a function of displacement. Similarly, power is also a vector dot product of vectors force and velocity. It is given by the equation: P=limt→∞ΔWΔt=limt→∞dWdt equation 6

It can be also expressed as:

P=FΔsΔt=Fv equation 7

P= F .v equation 8

One part of the experiment is where a hanging object tied in a string with a certain length, L. It is constantly raised where work and potential gravitation energy is computed.

On a motion of a body moving in a curved path.

ΣFx=F-Tsinθ=0

ΣFy=-W+Tcosθ=0

Dividing both equations:

F=Wtanθ

W=Fdlcosθ

where dl=dx=Rdθ

W=(Wtanθ)cosθRdθ

W=WR0θsinθdθ

W=WR(1-cosθ) equation 9

Aside from kinetic, another type of mechanical energy is the potential energy. It is due to position or configuration which is the possibility of work to be done. Change in the gravitational potential energy is the work done by gravity. It has an equation: PEg=mgΔy or mgh equation 10

Naturally for this case in our experiment, energy being used are both potential gravitational energy and kinetic energy. According to Law of Conservation of Energy, energy is neither created nor destroyed, but transform from one form to another. Law of Conservation of Energy states that the sum of the total energy in the universe is a constant quantity. In the experiment, we will determine the power of the fan cart by using the definition of work and energy conservation principle as well as to compute work for a motion along a curved path. It is also reflected how energy is transformed or conserved.

Experiment Proper

The first part of experiment is divided into two parts. In the first one, calculations of work and power of a fan cart is the primary concern. To do so, materials such as fan cart, track, smart timer, photogates, pan with loads, etc. are given to us in assembling the set-up. The fan cart has fan on it which aids it to move. The fan has wooden blades, so we are careful on using it while it is in motion. We set the track horizontally on the table, as 00 as possible to minimize errors. Initial determination of the force exerted by the fan was determined in a trial and error basis. The track is assumed to be frictionless – for an...

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