Aim: What are the different kinds of energy? Do Now: Take a
minute to write down on a piece of paper if you going to take the
regents exam or not. Include your name and section number. Put the
tally in the box. You may change your answer later. Homework:
Choose a topic from the list to write about Due 2/4 Finish the
worksheet due 2/13/15 New Project is due Feb 22 nd How do we know
something has energy and in what ways do we witness the effect of
something having energy? Agenda Do Now 2 min Regent's Tally Mini
Lesson 25 min What is Energy and what are its forms Activity 10 min
what are some of the energy types you know? determine the different
types of energy? Wrap up 8 min Exit slip Review 10 min Old concepts
review Working definitions Energy: the capacity to do work. Joule:
The unit for work and energy 1 J = 1 Nm = 1 kgm 2 /s 2 Video :
https://www.youtube.com/watch?v=aUa7I7D_myU Two main categories of
energy Kinetic Energy: Energy of motion A moving baseball can do
work A falling anvil can do work Potential Energy: Stored (latent)
capacity to do work Gravitational potential energy (perched on
cliff) Mechanical potential energy (like in compressed spring)
Chemical potential energy (stored in bonds) Nuclear potential
energy (in nuclear bonds) Kinetic Energy The kinetic energy for a
mass in motion is K.E. = mv 2 Example: 1 kg at 10 m/s has 50 J of
kinetic energy https://www.youtube.com/watch?v=ASZv3tIK56k KE
continue Kinetic energy is proportional to v 2 Watch out for fast
things! Damage to car in collision is proportional to v 2 Trauma to
head from falling anvil is proportional to v 2, or to mgh (how high
it started from) Hurricane with 120 m.p.h. packs four times the
punch of gale with 60 m.p.h. winds Aim: what is a closed system? Do
Now: Write down a scenario explaining where there is energy and
what kind. An example: A boy walks up a flight of stairs (uses
chemical energy converting it into mechanical energy which is
converted into potential energy at the top.) and then drops a penny
from the window (gravitational potential energy is converted into
kinetic energy as the penny falls). Homework: Choose a topic from
the list to write about Due 2/4 Finish the worksheet due 2/13/15
New Project is due Feb 22 nd How do we know something has energy
and in what ways do we witness the effect of something having
energy? Gravitational Potential Energy PE = mgh m = mass of the
object g = acceleration due to gravity h = height the object is at.
The higher the object is the more potential it has.
https://www.youtube.com/watch?v=aCdHEWWpWj8 Example Ball dropped
from rest at a height h (P.E. = mgh) hits the ground with speed v.
Expect mv 2 = mgh h = gt 2 v = gt v 2 = g 2 t 2 mgh = mg (gt 2 ) =
mg 2 t 2 = mv 2 sure enough Ball has converted its available
gravitational potential energy into kinetic energy: the energy of
motion Energy Conversion Energy can be converted between types
Energy cant be created or destroyed Doing work on something changes
that objects energy by amount of work done, transferring energy
from the agent doing the work
https://www.youtube.com/watch?v=Jnj8mc04r9E Energy Conservation The
total energy (in all forms) in a closed system remains constant
This is one of natures conservation laws Conservation applies to:
Energy (includes mass via E = mc 2 ) Momentum Angular Momentum
Electric Charge Total energy of a closed system KE initial + PE
initial = KE final + PE final mv 2 + mgh = mv 2 + mgh Total energy
in non ideal systems KE initial + PE initial = KE final + PE final
+ E lost mv 2 + mgh = mv 2 + mgh + Heat Work defined Work carries a
specific meaning in physics Simple form: work = force distance W =
F d Work explained Work can be done by you, as well as on you Are
you the pusher or the pushee Work is a measure of expended energy
Work makes you tired Machines make work easy (ramps, levers, etc.)
Apply less force over larger distance for same work Aim: How do we
find the energy stored in a spring? Do Now: 1. Write down the topic
you chose from the list and the date to present on it. 2. What is
the energy in a 5.0 kg cat on the third floor (9.0 m above the
ground) How fast will the cat be traveling before landing on the
ground? [ignore air resistance] Homework: Finish the worksheets due
2/13/15 the first article is Due 2/20 read about it by the 23New
Project is due Feb 22 nd How do we know something has energy and in
what ways do we witness the effect of something having energy? What
is the energy in a 5.0 kg cat on the third floor (9.0m above the
ground) How fast will the cat be traveling before landing on the
ground? [ignore air resistance] G: m = 5.0kg, h = 9.0m, g= 9.8m/s 2
U: PE =?, v=? E: PE = mgh KE = mv 2 PEi+ KEi = PEf +KEf PEi = KEf
mgh = mv 2 S:(5kg)(9.8m/s 2 )(9m) = (5kg) v 2 S: 441J = 2.5kg v m 2
/s 2 = v m/s = v = 13m/s Spring Equilibrium The equilibrium
position is the position that the spring naturally assumes when
there is no force applied to it. If a spring is not stretched or
compressed, then there is no elastic potential energy stored in it.
The spring is said to be at its equilibrium position. Hooks law F
spring = k x The force stored in a spring is equal to how elastic
it is (k) times the distance it is compressed or expanded (x).
Every spring has a different constant!! Elastic Potential Energy PE
spring = 0.5 k x 2 k = spring constant x = the distance the spring
is compressed or expanded. The energy stored in a spring or elastic
when it is removed from equilibrium. Activity Find the spring
constant and potential energy in your spring scale! What is Power?
Power is simply energy exchanged per unit time, or how fast you get
work done (Watts = Joules/sec) One horsepower = 745 W Power
examples Perform 100 J of work in 1 s, and call it 100 W Run
upstairs, raising your 70 kg (700 N) mass 3 m (2,100 J) in 3
seconds 700 W output! Shuttle puts out a few GW (gigawatts, or 10 9
W) of power! Do Now cat is back! G: m = 5.0kg, h = 9.0m, g= 9.8m/s
2, t= 0.7s Found: v = 13m/s, PE = 441 J U: Fg= ?, W=?, P=? E: Fg =
mg, S: Fg = (5kg)(9.8m/s 2 ) S:Fg = 49N Do Now cat is back! G: m =
5.0kg, h = 9.0m, g= 9.8m/s 2, t= 0.7s Found: v = 13m/s, PE = 441 J.
Fg= 49N U: Fg= ?, W=?, P=? E: W=fd S: W = (49N)(9m) S:W = 441J Do
Now cat is back! G: m = 5.0kg, h = 9.0m, g= 9.8m/s 2, t= 0.7s
Found: v = 13m/s, PE = 441 J. Fg= 49N, W = 441J U: Fg= ?, W=?, P=?
E: P=W/t S: P = (441J)/(0.7s) S:p = 630Watt Wow Curls !! Ms. Adams
Curly Cues have a mass of 25g each. As she pulls on one with a
force of 0.02N it expands a distance of 7 cm. What is the spring
constant for the curl Ms. Adam pulled? How much energy is stored in
her curl before it was released? How fast did was her curl
traveling back to equilibrium? How much work was done by the curl?
If it took 0.5 sec for it to go back what is the power of her curl?
Momentum Often misused word, though most have the right idea
Momentum, denoted p, is mass times velocity p = mv Momentum is a
conserved quantity (and a vector) Often relevant in collisions
(watch out for linebackers!) 1. Two pieces of flint rock produce a
visible spark when they are struck together. During this process,
mechanical energy is converted into (1) nuclear energy and
electromagnetic energy (2) internal energy and nuclear energy (3)
electromagnetic energy and internal energy (4) elastic potential
energy and nuclear energy 2. What is the total energy released when
9.11 10 31 kilogram of mass is converted into energy? (1) 2.73 10
22 J (3) 9.11 10 31 J (2) 8.20 10 14 J (4) 1.01 10 47 J E = mc 2 c=
speed of light in a vacuum = 3.00x10 8 m/s E = (9.11x kg)(3.00x10 8
m/s) 2 = 81.99x E= 8.20 x kgm 2 /s 2 3. A shopping cart slows as it
moves along a level floor. Which statement describes the energies
of the cart? (1) The kinetic energy increases and the gravitational
potential energy remains the same. (2) The kinetic energy increases
and the gravitational potential energy decreases. (3) The kinetic
energy decreases and the gravitational potential energy remains the
same. (4) The kinetic energy decreases and the gravitational
potential energy increases. 4. A 25-gram paper cup falls from rest
off the edge of a tabletop 0.90 meter above the floor. If the cup
has 0.20 joule of kinetic energy when it hits the floor, what is
the total amount of energy converted into internal (thermal) energy
during the cups fall? (1) 0.02 J (3) 2.2 J (2) 0.22 J (4) 220 J 5.
Regardless of the method used to generate electrical energy, the
amount of energy provided by the source is always greater than the
amount of electrical energy produced. Explain why there is a
difference between the amount of energy provided by the source and
the amount of electrical energy produced. [1] 6. When a teacher
shines light on a photocell attached to a fan, the blades of the
fan turn. The brighter the light shone on the photocell, the faster
the blades turn. Which energy conversion is illustrated by this
demonstration? (1) light thermal mechanical (2) light nuclear
thermal (3) light electrical mechanical (4) light mechanical
chemical (1)decreases, then increases (2) increases, only (3)
increases, then decreases (4) remains the same 7. In the diagram
below, an ideal pendulum released from position A swings freely to
position B. As the pendulum swings from A to B, its total
mechanical energy 8. Which graph represents the relationship
between the kinetic energy and the speed of a freely falling
object? Base your answers to questions 9 to 12 on the following: A
30.4-newton force is used to slide a 40.0-newton crate a distance
of 6.00 meters at constant speed along an incline to a vertical
height of 3.00 meters 9. Determine the total work done by the
30.4-newton force in sliding the crate along the incline. [1] G: F
= 30.4N, Fg = 40.0 N, d= 6m, h=3 m U: work =?? E: W = Fd S: W =
(30.4N)(6m) S: W = J A 30.4-newton force is used to slide a
40.0-newton crate a distance of 6.00 meters at constant speed along
an incline to a vertical height of 3.00 meters 10. Calculate the
total increase in the gravitational potential energy of the crate
after it has slid 6.00 meters along the incline. [Show all work,
including the equation and substitution with units.] [2] G: F =
30.4N, Fg = 40.0 N, d= 6m, h=3 m U: PE =?? E: PE = mgh S: PE =
(40N)(3m) S: PE = 120 J at the top 0 J at the bottom A 30.4-newton
force is used to slide a 40.0-newton crate a distance of 6.00
meters at constant speed along an incline to a vertical height of
3.00 meters 11. State what happens to the kinetic energy of the
crate as it slides along the incline. [1] G: F = 30.4N, Fg = 40.0
N, d= 6m, h=3 m U: KE =?? As the crate slide down the incline its
kinetic energy increases. A 30.4-newton force is used to slide a
40.0-newton crate a distance of 6.00 meters at constant speed along
an incline to a vertical height of 3.00 meters 12. State what
happens to the internal energy of the crate as it slides along the
incline. G: F = 30.4N, Fg = 40.0 N, d= 6m, h=3 m U: Internal energy
The internal energy of the crate increase as it slides along the
incline.