Objective 4 – Motion, Forces, and Energy
ENERGY_
Energy: ability to do work when a force is applied to matter.
Energy travels in waves and can be transformed but not created
(Law of Conservation of Energy.
Chemical
Mechanical
Electrical
Sound
Light
Thermal
Nuclear
Stores energy in molecules/bonds; this is the type of
energy food has; this is potential energy.
This is energy of motion (kinetic energy) and energy of
position (potential energy).
Moves energy by electrons flowing through materials;
electricity and lightening.
Vibrates through a longitudinal wave, requires matter to
move energy.
Travels as a wave; solar energy is one form of light
energy (solar energy is the ultimate source of energy on
Earth)
Caused by the motion of atoms, average kinetic energy is
a measurement of heat. Conduction, convection and
radiation are methods of heat transfer.
Energy generated by the splitting of atoms; happens on
stars and nuclear power plants.
ENERGY TRANSFORMATIONS_____________________
Energy can be transformed from on form to another. People
transform Energy to meet their needs.
Examples:
1) Chemical Energy from gasoline is converted to mechanical
energy when you drive a car_
_
2) Electrical energy is converted to light energy when you turn_
a lamp on_________________________________________
3) Mechanical energy from wind is converted to electrical_____
energy in windmills._________________________________
4)_Chemical energy from batteries is converted to sound energy
when you turn on the radio.
_______
WAVES______________________________________________
Wave: disturbance that transmits energy
Medium: substance through which a wave travels
Mechanical Waves: waves that require a medium, they have 2
basic wave motions transverse and longitudinal.
Transverse Waves:
Identify the following examples as kinetic energy (KE) or
potential energy (PE):
1. Holding a ball above the ground
2. Letting the ball drop
3. About to skydive
4. Falling from a plane to the ground
5. Which points will the cart have potential energy?
6. Which point will the cart have the MOST potential energy?
7. Which points will the cart have kinetic energy?
8. Which point will the cart have the MOST kinetic energy?
Identify the form(s) of energy the followings objects contain:
9. Vegetables
10. Light Bulb
11. Camp Fire
Wavelength
Amplitude
12. Flying Plane
Crest
13. Battery
Rest Position
List 2 examples of energy transformations (other than the ones
listed):
Amplitude
Trough
14.
Longitudinal Waves:
15.
16. What do waves carry (transmit)?
17. What is the difference between mechanical waves and
electromagnetic waves?
Electromagnetic Waves: waves that do not require a medium; can
travel through a vacuum (empty space)
18. You hear a train in the distance, what is the medium the
wave has traveled through? Which mechanical wave motion
has occurred?
WORK AND SIMPLE MACHINES
__________
Machine: tool that makes work easier by changing the size or
direction of the force put into it
List a real tool that represents each of the following types of
simple machines:
19. Lever
Simple Machines:
Levers -
20. Pulley
21. Wedge
22. Inclined Plane
Pulleys -
23. Screw
Wedge -
24. Wheel and Axle
25. In which diagram (1 2 or 3) will it require the MOST force
to raise the box the same distance?
Inclined Plane:
Screw:
Wheel and Axle:
FORCE
___________________
Force: a push or pull; force is needed to start or stop the motion of
an object; force is measured in Newtons (N)
Work: a force is said to do work when it results in movement,
work is the product of a force and distance
Work= Force x distance
Contact Force: an object exerts a force on another object when in
contact; friction, push or pull.
Long Range or Noncontact Force: forces that can act on objects
from a distance; gravity, magnetism or electricity.
_
Balanced Forces: opposing (opposite) forces that are equal in size;
this does not change the speed or the direction of an object (no
acceleration).
Unbalanced Forces: forces that are not equal in size; this does
change the speed and/or the direction of an object (acceleration).
Examples: Balanced and Unbalanced Forces
___
__________
__
_
COMMON FORCE
_____________________
_
Gravity: a force that pulls objects in the universe toward each
other; gravity varies by location in the universe; acceleration due to
gravity is:
9.8 m/s2 on Earth
Weight: measures the force of gravity on the mass of an object;
Weight = mass x gravity
Friction: the resistant force to motion.
26. In which diagram (1 2 or 3) will it require the LEAST
force to raise the box the same distance?
26. In which diagram (A B or C) will it take the MOST force to
raise the object?
27. In which diagram (A B or C) will it require the LEAST
force to raise the box the same distance?
28. The above diagrams are showing what type of lever?
29. How much work does an elephant do while moving a
circus wagon 20 meters with a pulling force of 200N?
30. Angela uses a force of 25 Newtons to lift her grocery bag
while doing 50 Joules of work. How far did she lift the grocery
bags?
31.
Draw an example of a balanced force (other than the one
already show), be sure to include Newtons (N) and Net Force
(direction):
Draw an example of an unbalanced force (other than the one
already show), be sure to include Newtons (N) and Net Force
(direction):
MOTION
_____________________
Motion: change in position
Distance: length of the path traveled
Speed: how fast you are changing
position
Speed = distance / time
Velocity: describes speed in a given
direction
Acceleration: any change in motion
Displacement: distance from the
starting position to the ending position
_
32. If this graph
represents the speed of a
car, how fast is the car
going?
Example: Speed Graphs
Distance, m
Positive Acceleration Speed Graph
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
Time, s
time, s
distance, m
speed, m/s
0
0
0
1
25
25
2
50
25
3
75
25
Constant Speed: the line is straight; every second the object_ ___
moves the same amount of distance; instantaneous speed is always
the same_________________________
___
33. Between what hours is Kara stopped?
34. Between what hours is she going the fastest?
35. Between hour 1 and hour 2 Kara went from 5 km to 7 km.
What was her speed for that hour?
Distance, m
Positive Acceleration Speed Graph
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
Time, s
time, s
distance, m
speed, m/s
0
0
0
1
10
25
2
30
25
3
75
25
Changing Speed: the line is curved up if the object is going faster,
the line is curved down if the object is slowing down___________
Calculate the speed of the train between each point to be able to
answer the following questions.
36. Between what sets of points is the train going the fastest?
37. Between what points was the train stopped?
38. Between what points was the train traveling back in the
direction it was coming from?
NEWTON’S LAWS OF MOTION
Newton's first law of motion:
An object at rest stays at rest and
an object in motion stays in
motion with the same speed and
in the same direction unless acted
upon by an unbalanced force.
Inertia: the resistance an object
has to a change in its state of motion.
__________
Examples of Newton’s first law:
 Blood rushes from your head to your feet while quickly
stopping when riding on a descending elevator.
 A brick is painlessly broken over the hand of a physics teacher
by slamming it with a hammer.
 While riding a skateboard, you fly forward off the board when
hitting a curb or rock.
Newton's second law of motion
can be formally stated as:
Acceleration is produced when a
force acts on a mass. The greater the
mass (of the object being
accelerated), the greater the amount
of force needed (to accelerate the
object).
List 2 examples of Newton’s first law of motion (other than the
ones listed)
39.
40.
2
41. Sally has a car that accelerates at 5 m/s . If the car has a
mass of 1000 kg, how much force does the car produce?
42. Sally wants to accelerate even faster than in problem #41,
so she removes 500 kg of mass from her car. How fast will her
1500 kg car accelerate if it produces 5000 N of force?
43. What is the mass of a falling rock if it produces a force of
147 N?
F= ma
The force of gravity on an object
on Earth is 9.8 m/s2 .
Newton's third law of motion:
For every action, there is an equal
and opposite reaction.
44. What is the mass of a truck if it produces a force of 14,000
N while accelerating at a rate of 5 m/s2 ?
Examples of Newton’s third law:
 Shopper: The woman pushing
a shopping cart feels an opposite force applied by the cart on
her.
 Baseball player: When the baseball player hits the ball with his
bat, the ball reacts by pushing back on him. The player feels
this as a jerk backwards when the bat contacts the ball.
 Fish: Fish propel themselves forward by pushing water back,
behind them. The water reacts by pushing the fish in the
opposite direction, forward.
45. What is the acceleration of softball if it has a mass of 0.5
kg and hits the catcher's glove with a force of 25 N?
46. Your own car has a mass of 2000 kg. If your car produces
a force of 5000 N, how fast will it accelerate?
List 2 examples of Newton’s third law of motion (other than
the ones listed)
47.
48.