1. TAKS Physics Review
DAY 1

2. Objective 5 - Physics Force and motion Newton’s laws Waves
Conservation of energy
Heat transfer
Electrical circuits
Simple Machines

3. Motion: Speed
Speed (S) - a distance traveled in a given amount of time.
LOOK at the formula on your chart:
Speed = Distance Traveled
Time
In other Words: Speed is just the distance traveled over time.

4. Speed Example: I.4A 10th Spring 2003
First let’s list what we know and what we want to find out.
We know: Distance traveled= 150 km
Time =2.5 Hours
We want to find out: ??Average speed???

5. So what is the difference between speed and velocity?
Velocity is the vector quantity of speed.
Remember: a vector needs to have a magnitude and direction.
Therefore: Velocity is just the speed (magnitude) in a given direction.
Let’s come up with some examples!!!

6. Motion: Acceleration
When an object's velocity changes, it accelerates. Acceleration shows the change in velocity in a unit time.
Let’s look at the formula:
Acceleration = final velocity – initial velocity
change in time
In words: Acceleration is just the change of velocity over a period of time.

7. Example
A roller coaster has a velocity of 3 m/s and an acceleration of 15 m/s2. How many seconds will it take the roller coaster to reach its maximum velocity of 27 m/s?

8. First let’s list what we know and what we want to find out.
The current (or initial) velocity: 3 m/s, vi
The acceleration: 15 m/s2, a
The maximum (or final) velocity: 27 m/s, vf
We want to find out how much time it will take the roller coaster to accelerate from 3 m/s to 27 m/s.

9. We need to solve for time so we need to rearrange our formula and solve for change in time.
First:
acceleration x change in time = final velocity – initial velocity
Then solve for time:
change in time = final velocity – initial velocity
acceleration
SOLVE IT!!!

10. Motion: Momentum From our formula chart: Momentum = mass x velocity
Objects in motion are said to have a momentum. This momentum is a vector. It has a size and a direction. momentum is equal to the mass of the object multiplied by the object's velocity. The direction of the momentum is the same as the direction of the object's velocity.
From our formula chart:
Momentum = mass x velocity

11. Momentum therefore m1v1 = m2v2
Momentum is a conserved quantity in physics.
One object might change momentum, say losing some momentum, as another object changes momentum in an opposite manner, picking up the momentum that was lost by the first.
ρ1= ρ2
therefore
m1v1 = m2v2

12. Example 7. The 500 g cart is moving in a straight line
at a constant speed of
2 m/s. Which of the
following must the 250 g
toy car have in order to
maintain the same momentum as the cart?
F An acceleration of 5 m/s2 for 2 seconds
G A potential energy of 20 J
H A constant velocity of 4 m/s
J An applied force of 5 N for 5 seconds

13. Newton’s Laws Vocabulary: Force- A push or a pull
I. Law of Inertia
II. F= ma
III. Action-Reaction
Vocabulary:
Force- A push or a pull
Unbalanced force – when one force is greater than the other resulting in a change in motion.
Inertia- the tendency of an object to resist a change in its motion.
Friction- an unbalanced force that opposes motion.

14. 4 Types of Friction Sliding friction: ex. Ice skating
Rolling Friction: ex. Bowling
Fluid Friction: (gases or liquids) ex. Air or water resistance.
Static Friction – initial friction when moving an object.

15. Newton’s Laws Newton's First Law of motion (Law of Inertia)
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.  

16. Newton’s Laws cont. Newton's second Law of motion
(Law of acceleration)
The second law states that the acceleration of an object is dependent upon two variables –
the net force acting upon
the object and the mass
of the object.

17. Newton’s Laws cont. Newton's third Law of motion
(Law of action and reaction)
For every action, there is an equal and opposite reaction

18. Back to our Formula Chart
Force - a push or a pull on an object that will result in the acceleration of the object. F = ma
Force is measured in
NEWTONS (N)
A newton is simply a
kg*m s2

19. Formula Chart contd.
Work - occurs when a force causes an object to move in the direction of the force
W=Fd
Work is measured in
JOULES (J)
A joule is simply a newton*meter

20. Formula Chart cont.
Power - The amount of work that gets done over a certain amount of time.
P= W_ t Power is measured in
WATTS (W)
A watt is simply a joule s

21. Formula Chart cont.
%efficiency is simply the relation of how much work are you getting out related to how much work you actually put into a process.
From our chart:
%efficiency = work output
work input
X 100

22. Sample Problems
You must exert a force of 4.5 N on a book to slide it across a table. If you do 2.7 J of work in the process, how far have you moved the book?
a. .30 m
b. .79 m
c. .60 m
d. 1 m

23. Sample Problems cont.

24. Sample Problems cont.

25. Sample Problems cont.

26. Sample Problems cont.

27. Sample Problems cont.

28. Sample Problems cont.

29. Energy Is defined as the Ability to do Work There are two Types:
Kinetic (Energy of Motion) and
Potential (Stored Energy)

30. Kinetic Energy KE = ½ m v 2 Ex: A moving car has the ability to
do work on the light pole if it hits it.

31. Potential Energy 2 possibilities
Gravitational PE -Object lifted to some height
Elastic PE - A stretched or compressed object (spring or rubber band)

32. Gravitational Potential Energy or Will it fall?
GPE = m g h
m is the mass of the
object in Kg,
g is the acceleration
due to gravity which is
9.8 m/s2 on earth and
h is the height in meters

33. Use the formula page! PE = mgh
41 What is the potential energy of the rock? A 59,900 joules B 64,600 joules C 93,100 joules D 121,600 joules
m = 95 kg g = 9.8 m/s2 h = 100 m
95 kg x 9.8 m/s2 x 100 =
93,100 joules C

34. Law of Conservation of Energy
Energy can change forms, but is never created nor destroyed
Loss in one form = gain in an another form
A falling object speeds up as it falls to the ground; PE decreases as KE increases. The KE it has at impact = the PE it had before it fell.

35. Example: A falling object speeds up as it falls to the ground;
PE decreases as KE increases, the KE it has at impact with the ground is equal to the PE it had before it fell

36. Sample Problems

37. Sample Problems cont.

38. Sample Problems cont. 38

39. PHYSICS REVIEW DAY 2

40. Waves - Energy carried by rhythmic disturbances
Two types:
1. E.M. radiation move through empty space
2. Mechanical require a medium (air, water or any type of matter) for movement

41. Waves - 2 Types

42. All waves have similar properties
Frequency- the number of vibrations per second or the speed of the movement of the vibrating particles
Amplitude – the size of the movement of the vibrating particles
Both are controlled by the disturbance that created the waves

43. Velocity of all waves - v=f λ
f-frequency and λ is wavelength (distance between identical points on two consecutive waves)
Reflection- bounce off barriers in regular ways
Refraction- waves can change direction when speed changes

44. The speed of a wave is the distance the wave travels in one unit of time. The speed of a wave is measured in units per second (m/s). A waves velocity is its speed in a particular direction.
Frequency is a measure of how many wavelengths pass a particular point in one unit of time. Measured in hertz (hz). One hertz is equal to one wave per second.
-So, if four complete wavelengths pass you every second, the frequency is four waves per second, or four hertz.

45. J 3300 Hz And the answer is? Use the formula chart!!!
38 At 0°C sound travels through air at a speed of 330 m/s. If a sound wave is produced with a wavelength of 0.10 m, what is the wave’s frequency?
F Hz
G 33 Hz
H 330 Hz
J 3300 Hz
Use the formula chart!!!
Velocity = f λ OR
330 m/s = f x m

46. Transverse Waves
In Transverse Waves particles vibrate at right angles to the direction the wave travels.
Ex. E. M. Waves, waves on a slinky or rope coil, ocean waves

47. Longitudinal or Compress ional Waves
Vibrating particles move back and forth along the direction of the wave velocity
Parts consist of compressions and rarefactions
Ex. Sound Waves

48. Sample Problem

49. Sound Waves move through matter not through empty space.
32 One tuning fork is struck and placed next to an identical fork. The two forks do not touch. The second tuning fork starts to vibrate because of —
F interference
G the Doppler effect
H resonance
J standing waves
Resonance is the vibration of another object struck by a wave of the correct frequency. Since the forks are identical, the second one receives the correct frequency to begin vibrating.

50. Heat Transfer Difference between Heat and Temperatute.
Heat is energy that is transported from warmer objects to colder objects.
Temperature is a measure of the amount of kinetic energy and momentum atoms and molecules have in an amount of gas, liquid, or solid.

51. CONDUCTION
transfer of heat through a SOLID, where kinetic energy is transferred from molecule to molecule
Objects MUST touch
THINK of a CONDUCTOR

52. CONVECTION
Convection: transfer of heat that occurs from the motion of fluid in LIQUID or GAS that is caused by differences in temperature

53. RADIATION
transfer of heat by electromagnetic WAVES that are produced by thermal motion of molecules and atoms
SUN!!!
NO TOUCHING

54. Sample Problems

55. Sample Problems cont.

56. Sample Problems cont.

57. Electrical Energy - Moving electrons in a path is electricity
Electrical Potential Difference (v) is measured in Volts
The rate of moving electric charges, Electric Current (I), is measured in Amperes
Resistance or opposition to the movement of the energy is called Resistance (R).

58. Circuits – 2 types Series circuits are the most simple.
One (1) path for the current to travel.
Contains an energy source, a path, and a load (something for it to do, like a lamp)

59. Circuits – 2 types
Parallel circuits provide more than one path for the current to travel.
Most circuits are parallel, since if one lamp goes out, the others can stay lit.

60. cause the light bulb to stop glowing?
Which switches, if opened, will
cause the light bulb to stop glowing? Q R
H. S
J. T
It is the only switch in series to both the battery and light.

61. USE THE FORMULA SHEET!! V = I R so, 9V = I x 2 ohms or 4.5 amps
What is the current in a copper wire that has a resistance of 2 ohms and is connected to a 9 volt electrical source?
A amp
B amps
C amps
D amps
V = I R so,
9V = I x 2 ohms or 4.5 amps

62. Remember Use your Equation Sheet Use your Calculator
Use your Periodic Table