1. Motion , Forces and Energy
TAKS Objective 5
Motion , Forces
and Energy

2. Energy Is defined as the Ability to do Work Energy has Two Types:
Kinetic (Energy of Motion) and
Potential (Stored Energy)

3. 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.

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

5. 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

6. 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

7. 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.

8. 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

9. Energy can be conserved in Non-Mechanical forms
The chemical energy in a battery transforms into electrical energy
Any reaction where more energy is given off than is used to start it is Exogonic
An Endogonic reaction absorbs energy and causes cooling

10. 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).

11. 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)

12. 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.

13. 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.

14. 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

15. Thermal Energy
A body contains internal KE due to the motion of its atoms ( they are constantly wiggling and jiggling)
Thermal Energy is the total internal KE of a body
Temperature is the average KE of a body

16. Heat- Transfer of Thermal Energy
Three forms of heating:
1. Conduction-direct contact, a pot heating on a stove (solids)
2. Convection- heating by circulating fluids, (gas and liquid) heating from a fireplace
And. . .

17. 3. Radiation – Transfer of Electromagnetic (E.M.) Energy
Objects are heated when exposed to infrared radiation
The suns heats the earth by sending infrared radiation along with other forms of E.M. energy 3.0 x 108 meters through empty space

18. Heat moves by conduction in solids since the particles are close together and vibrate. . .
43 Heat convection occurs in gases and liquids. Heat convection does not occur in solids because solids are unable to —
A absorb heat by vibrating
B transfer heat by fluid motion
C emit radiation by reflecting light
D exchange heat by direct contact
Solids do radiate heat to their surroundings

19. 2 The primary way liquids and gases transmit heat is by the process of —
F reflection
G conduction
H radiation
J convection
Fluid heat movement is convection. Fluid motion occurs in liquids and gases.

20. 50 A solar heater uses energy from the sun to heat water
50 A solar heater uses energy from the sun to heat water. The heater’s panel is painted black to —
Convection is movement of heat in fluid matter, heat loss would be from a solid exterior – Not G
F improve emission of infrared radiation
G reduce the heat loss by convection currents
H improve absorption of infrared radiation
J reduce the heater’s conducting properties
Painting a substance will not change its conductivity – That is a property of metals. It would have to be made of a different substance to change that: Not J
Emission is giving off – we want to absorb: Not F

21. Nuclear Reactions Fusion occurs when two atoms
combine to form a new element.
The sun produces all of its
energy through fusion.
Two hydrogen atoms combine
to form a Helium atom from the
great gravitational forces and
pressure in the sun’s core

22. Nuclear Reactions - Fission
Fission is the splitting of nucleii of large atoms such as Uranium and Plutonium
Produces large amounts of infrared radiation and other forms of E.M. Energy such as Gamma Rays
Currently, it is the main form of Atomic Energy on Earth

23. Radiant Energy or Electromagnetic Energy (EM)
All radiant energy travels at 3.0 x 108 m/sec in space
Velocity of a wave = wavelength x frequency
Visible light is just one type of EM Energy

24. Electromagnetic Spectrum
All of the forms of radiation given off by vibrating electric charges
Radiation comes in the form
of vibrating or “throbbing
bundles of energy” called
photons
The frequency of the vibrating
electric charges determines
which type and how much
energy will be given off

25. The entire E.M. Spectrum in order from lowest to highest frequency
Radio waves: AM and FM
Microwaves: cooking
Infrared: heat
Visible: (ROYGBV)
Ultraviolet: tanning
Xrays: medical
Gamma:
deadly radioactivity

26. 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

27. Waves - 2 Types

28. 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

29. 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

30. J 3300 Hz Use the formula chart!!! Velocity = f λ OR
And the answer is?
J 3300 Hz
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

31. 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

32. 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

33. Sound Waves are Compression Waves
Sound is produced when a compression is made.
It requires a producer and a medium to travel through.
The more elastic the object, the faster sound travels.

34. Sound acts like other waves
Echoes are reflected sound waves
Sonar uses echoes to judge distance to obstructions
Human hearing is 20-20,000 Hz, below 10 Hz is infrasonic, and above 20,000 Hz is ultrasonic.

35. 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.

36. Forces and Motion Forces can create changes in motion (acceleration)
Deceleration is negative acceleration

37. Motion can be described as
a change in an object’s position
Average velocity (speed) is the change of position of an object over time

38. Velocity Graphs V = distance time
Velocity (v) is the slope (rise over run) of a position (d) vs. time (t) graph

39. 40 The diagram represents the total travel of a teacher on a Saturday
40 The diagram represents the total travel of a teacher on a Saturday. Which part of the trip is made at the greatest average speed?
F Q
G R
H S
J T
How do we work this one?
Calculate v = d/t for each segment.

40. Acceleration Graphs
Acceleration (a) is the slope of a velocity (v) vs. time (t) graph
Plotted on a distance vs. time graph, acceleration is an exponential curve

41. Acceleration is a change in an objects velocity (speed or direction)
When an object’s speed changes over time it is accelerating (or decelerating)
A = vfinal – vinitial
time
Units for acceleration m/s/s or m/s2

42. Definition of a Force
A Force is a push or a pull

43. Balanced Force
A force that produces no change in an object’s motion because it is balanced by an equal, opposite force.
If you were to add these forces they would = 0

44. 4 The picture shows the position of a ball every 0
4 The picture shows the position of a ball every 0.25 second on a photogram. Using a ruler, determine the velocity of the ball.
F 3.5 cm/s
G 10.5 cm/s
H 14.0 cm/s
J 28.0 cm/s

45. Use the ruler on the side of the chart and the equation for velocity
Use the ruler on the side of the chart and the equation for velocity. The answer was H.
Measure from the center of ball 1 to the center of ball 2 and multiply by 4.

46. Unbalanced Forces
Are forces that results in an object’s motion being changed. +
Add together to equal greater force.

47. Friction
A force that acts in a direction opposite to the motion of two surfaces in contact with each other.

48. Friction Friction causes an object to slow down and stop.
Since the amount of energy stays constant, the energy becomes heat.
Air resistance is an another example of friction.
Lubricants or grease reduce friction.

49. Newton’s 1st Law of Motion
Object in motion stays in motion

50. Newton’s 1st Law of Motion
And Objects at rest stay at rest

51. Newton’s 1st Law of Motion
Until they are acted upon by unbalanced forces.

52. Inertia or Newtons 1st Law
Tendency for an object to stay at rest or moving in a straight line at a constant speed.
The mass (m measured in kg) of an object determines its inertia
Inertia comes from the Latin word meaning lazy.

53. Newton’s 2nd Law of Motion
Force = Mass X Acceleration
F=ma
Weight (pull of gravity) is a
commonly measured force, calculated by F=mg, g is the acceleration due to gravity 9.8 m/s2

54. Newton’s 2nd Law of Motion
The greater the mass of an object, the greater the force required to change its motion.

55. Newton’s 2nd Law of Motion
The greater the acceleration of an object, the greater the force required to change its motion.

56. Formula chart says F=ma, m is mass in kg, a is acceleration in m/s2.
11 The frog leaps from its resting position at the lake’s bank onto a lily pad. If the frog has a mass of 0.5 kg and the acceleration of the leap is 3 m/s2, what is the force the frog exerts on the lake’s bank when leaping?
A 0.2 N
B 0.8 N
C 1.5 N
D 6.0 N
Formula chart says F=ma, m is mass in kg, a is acceleration in m/s2.
So, .5 kg x 3 m/s2= 1.5 N

57. Newton’s 3rd Law of Motion
For every action force there is an equal and opposite reaction force.

58. Newton’s 3rd Law of Motion
All forces come in action-reaction pairs
Ex: feet push backward on floor, the floor pushes forward on feet

59. 27 A ball moving at 30 m/s has a momentum of 15 kg·m/s
27 A ball moving at 30 m/s has a momentum of 15 kg·m/s. The mass of the ball is —
A 45 kg
B 15 kg
C 2.0 kg
D 0.5 kg
Formula Page says that Momentum = Mass x Velocity
So 15 kg.m/s = M x 30 m/s solving for M it is:

60. Work Work: using a force for a distance W = F x d
The work done by forces on an object = changes in energy for that object.
Work and Energy are measured in Joules
1 Joule=1 Newton • meter

61. Use the formula Work = Force x distance
42 How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N?
F 300 J
G 750 J
H 1,000 J
J 15,000 J
Use the formula Work = Force x distance
Force of 20 N x 15 meters = 300 Joules Answer:

62. Why use a machine?
In an ideal (perfect) machine the work put into the machine (Win) = the work put out by that machine (Wout)

63. Machines make work easier
The ideal mechanical advantage of a machine (IMA) of a machine is the number of times the output force is larger than the input force IMA=Fout/Fin
A machine can only make this happen by moving the input force through a farther distance than the output force
Fin • din=Fout • dout

64. 48 The diagram shows an electric motor lifting a 6 N block a distance of 3 m. The total amount of electrical energy used by the motor is 30 J. How much energy does the motor convert to heat? F 9 J G 12 J H 18 J J 21 J

65. Work Input = 30J done by the motor
Work Output = Resistance Force x Resistance Distance
Workout = 18J = 6N x 3m
The difference is lost as heat due to friction, which is 30J – 18J = 12J
Answer G

66. Real Machines use Energy
No real machine is 100 % efficient. i.e. none put out more work than is put in
Efficiency of a machine is work output/work input X 100 %
Eff = Wout X 100%
Win

67. Machines use power
Power: the rate at which energy is used (work is done)
P=Work/time
Power is measured in H.P. or watts
1 watt = 1 Joule
1 sec

68. 45 If a force of 100 newtons was exerted on an object and no work was done, the object must have —
A accelerated rapidly
B remained motionless
C decreased its velocity
D gained momentum
Work = Force x Distance
Work = 0 Force = 100 N so
0 J = 100 N x d
distance must be 0
It did not move!

69. 6 Types of simple machines
Some Simple Machines:
Inclined planes
Screws
Pulleys
Wheel and axle
Levers
Wedge

70. Universal Law of Gravitation
All objects in the universe attract each other by the force of gravity

71. Universal Law of Gravitation
1) the mass of the object doing the pulling, and
Gravity varies depending on two factors:
2) the distance from the center of that object

72. On Earth gravity = 9.8 m/s/s
For every second that an object falls its speed increases by 9.8 m/s

73. Weight= Mass (m) X gravity (g)
Weight Unit of mass = kg
Unit of acceleration = m/s/s
Unit of weight = Newton
1 Newton= about ¼ pound

74. USE THE FORMULA PAGE . 1 2 3 4 5 6 7 8 9
Some of the problems require you to grid in an answer. Make sure you pay attention to the decimal point in the square in the middle.