Work, Kinetic Energy and Potential Energy
6.1 The Important Stuff 6.1.1 Kinetic Energy
For an object with mass m and speed v, the kinetic energy is defined as K = 1mv2
2
(6.1)
Kinetic energy is a scalar (it has magnitude but no direction); it is always a positive number; and it has SI units of kg · m2/s2. This new combination of the basic SI units is
known as the joule:
As we will see, the joule is also the unit of work W and potential energy U. Other energy
1joule = 1J = 1 kg·m2 (6.2) s2
units often seen are:
6.1.2 Work
1erg=1g·cm2 =10−7J 1eV=1.60×10−19J s2
When an object moves while a force is being exerted on it, then work is being done on the object by the force.
If an object moves through a displacement d while a constant force F is acting on it, the force does an amount of work equal to
W =F·d=Fdcosφ (6.3)
where φ is the angle between d and F.
All the angles of reflection are +3° off, so systematic error.
The device used to measure the angle might be miscalibrated or have incorrect markings.
Answer:
Explanation:
We know that for a capacitor 
, where <em>Q </em>is the charge of one plate, <em>C</em> the capacitance and <em>V</em> the potential between the plates.
We also know that 
, since 
is the surface charge density and <em>A</em> the area of the plate (both equal in our case).
Putting all together:
Which for our values is:
Where we notice that the S.I. units combination FV/C must not have units (we can verify it directly from their definitions or we notice that 
is enough to describe an area).
