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.
Answer:
Distance = 0.738 m
Explanation:
Solution:
<u>
First convert Km/h into m/s.</u>
75 km/h * 1000 m/km * 1 hr/3600 sec = 20.8333 m/s
<u>According to third equation of motion:
</u>
– 
= 2 * acceleration * distance
<em>
Vf= final velocity </em>
<em>Vi= initial velocity</em>
putting values in third equation of motion....
– 
= 2 * (-30 * 9.8) * distance
note:
negative sign is due to deceleration
Distance = 0.738 m
Answer:
Positively charged objects have electrons; they simply possess more protons than electrons.
Explanation:
2. An object that is electrically neutral contains only neutrons. Electrically neutral atoms simply possess the same number of electrons as protons.
<h3>Information:</h3>
If an atom has an equal number of protons and electrons, its net charge is 0. If it gains an extra electron, it becomes negatively charged and is known as an anion.
<h3>Tips:</h3>
If it loses an electron, it becomes positively charged and is known as a cation.
<h2>I hope this answers help you! :></h2>
The answer should be B.
Hope it helped you.
