1.2 Work and Energy

Question 1

Equation for work done?

Answer 1

W = Fx 
where 
w = energy/work done 
F = force 
x = distance moved

Question 2

Equation for gravitational potential energy

Answer 2

GPE = mgh 
where 
GPE = gravitational potential energy 
m = mass 
g = acceleration due to gravity  
h = change in height

Question 3

Equation for kinetic energy?

Answer 3

Ek  = 1/2mv^2 
where 
Ek = kinetic energy 
m = mass 
v = velocity

Question 4

Equation for elastic potential energy?

Answer 4

EPE = 1/2kx^2 
where 
EPE = elastic potential energy 
k = spring constant (stiffness) 
x = extension

Question 5

What is the mechanical energy?

Answer 5

Sum of potential and kinetic energy. It is associated with the position and motion of system

Question 6

What is the principle of conservation of energy

Answer 6

energy can neither be destroyed nor created, but merely transferred from one form to another

Question 7

How can kinetic energy be written in terms of momentum?

Answer 7

Ek = p^2/2m

Question 8

How do we derive this?

Answer 8

Mix together Ek = 1/2mv^2 and p = mv

Question 9

Do these equations work for relativistic particles?

Answer 9

No, they are travelling too fast. (near the speed of light)

Question 10

Is momentum conserved when no external forces are acting on the system?

Answer 10

Yes

Question 11

Does that mean that kinetic energy is also conserved?

Answer 11

No, it is usually not, it can be transferred to other energy stores. (heat,internal(thermal))