Transcript Work, distance and force

Energy
Work

Motion

Direction

Motion must be
in the same
direction of the
apply force.
Units
 Force
 Distance
 work
 Newton
(N)
 Meter (m)
 Joules (J)
Equation
 Work
 Distance
 force
 w=
Fxd
 D = w/f
 F = w/d
Potential energy
Energy store or waiting for being use.
 Potential energy cannot be transferred.

Kinetic energy

Motion, movement

Kinetic energy can be
transferred from one
moving object to
another.
Kinetic Energy
Potential Energy
Sound
Gravitational (GPE)
Mechanical (objects
move)
Radiant
(electromagnetic
spectrum)
Thermal (heat)
Mechanical (objects in
position…ready)
Nuclear (energy stored
in nucleus)
Electrical
Chemical (stored in
particles)
We have been taught that:

Every (Electrical)
Child (Chemical)
Knows (Kinetic)
Pork (Potential - Gravitational. lift. Or elastic. spring)
Sausages (Sound)
Have (Heat)
No (Nuclear)
Legs (Light)

Work done = Force x _______
 distance
 acceleration
 velocity
 speed
Units
 Force
 Distance
 work
 Newton
(N)
 Meter (m)
 Joules (J)
Equation
 Work
 Distance
 force
 w=
Fxd
 D = w/f
 F = w/d
1 joule = 1 _______
m2
 Kg . m2/s2
N m
 N 2 m2
N
Which form of energy does the
flowing water possess?
.
 gravitational
energy
 potential energy
 electrical energy
 kinetic energy
A coolie carries a load of 500 N to a
distance of 100 m. The work done by
him is _________.
5
N
 50,000 Nm

0
 1/5 N
The type of energy possessed by a
simple pendulum, when it is at the
mean position is

1. kinetic energy
 2.
potential energy
 3. potential energy + kinetic energy
 4. sound energy
According to the scientific definition
of work, pushing on a rock
accomplishes no work unless there
 movement.
a
net force.
 an opposing force.
 movement in the same
direction as the
direction of the force.
Which of the following is a form of
energy that is a kind of potential
energy?
 radiant
 Electrical
 Chemical
 none
of the above
Potential
energy
cannot be
transferred.
Electrical energy can
be converted to:




chemical energy.
mechanical energy.
radiant energy.
any of the above.
Units
 Force
 Distance
 work
 Newton
(N)
 Meter (m)
 Joules (J)
Equation
 Work
 Distance
 force
 w=
Fxd
 D = w/f
 F = w/d
Most all energy comes to and leaves
the earth in the form of




nuclear energy.
chemical energy.
radiant energy.
kinetic energy.
The law of conservation of energy is
basically that _________.
 energy
must not be used up faster than
it is created or the supply will run out.
 energy should be saved because it is
easily destroyed.
 energy is never created or destroyed.
 you are breaking a law if you needlessly
destroy energy.
The most widely used source of
energy today is:




A)
B)
C)
D)
coal.
petroleum.
nuclear.
water power.
Which quantity has the greatest
influence on the amount of kinetic
energy that a large truck has while
moving down the highway?
A)
B)
C)
D)
mass
weight
velocity
size
Which of the following statements is
/ are CORRECT?
 Inter-conversion
of kinetic energy and
potential energy is only valid in the system of
roller coaster and simple pendulum.
 A hydroelectric power plants use the interconversion of kinetic energy and potential
energy to generate electricity.
 We can make use of conservation of energy
to create energy.
A construction worker holds a heavy
tool box. How much work is done by
the worker?
 FGd
FGd
 mgh
 ½ mv2
 zero

An example of Kinetic Energy
would be:
a moving car
 a stretched rubber band
that was just released
 a charge particle in an
electric field
 all of the above

Units
 Force
 Distance
 work
 Newton
(N)
 Meter (m)
 Joules (J)
Equation
 Work
 Distance
 force
 w=
Fxd
 D = w/f
 F = w/d
An example of Potential Energy
would be:




a moving car
a battery
a book resting on a table
both b and c
Which is not an example of Solar
Radiation
 Microwaves
 Magnetism
 gamma
rays
 visible light
An example of a system having both
kinetic and potential energy would
be:
a book resting on a table
 a piece of sugar
 an object in free fall
 a stretched rubber band

Which of the following statements is
not correct
 energy
is the capacity to do
work
 Work can be express as Force
x Distance
 power is the amount of work
done in a unit of time
 the unit of power is the joule1.
A horizontal force of 200 N is
applied to move a 55 kg television
set across a 10 m level surface.
What is the work done by the 200 N
force on the television set?
 550
J
 6000 J
 2000 J
 11000 J
A child pulls a balloon for 12 m with a
force of 1.0 N at an angle 60
below horizontal. How much work
does the child do on the balloon?
 –10
J
 6.0 J
 –6.0 J
 12 J
Which of the following energy forms
is associated with an object due to
its position?
 potential
energy
 total energy
 positional energy
 kinetic energy
How much work would this 10 N
force acting over 10 m do on a 10 kg
object?
 a)
0J
 b) 70.7 J
 c) 100 J
 d) 980 J
 e)1000 J
A 10 kg mass is held 1.0 m above a
table for 25 s. How much work is
done during that
 10
J
 250 J
 9.8 J
 980 J
 none
A rock weighing 10 newtons is lifted a distance d
from the ground. The work done by the force
that lifts the rock is 10 joules. The rock is then
dropped on a wooden stake, thus driving the
stake into the ground. The distance d is most
nearly _________.
 0.01 m
 0.1 m
1 m
 10 m
 100m
Solve using all procedure
 How
much work is done on a
bookshelf being pulled 5.00 m at an
angle of 37.0 from the horizontal?
The magnitude of the component of
the force that does the work is 43.0
N.
 W= f x d
 = 43.0N x 5.00N
215J
Potential or Kinetic?
K
P
K
P
k
Running in a marathon.
 Car in the parking lot
 Air across the classroom
 Pencil over the desk
 Eat candy



How much work is done when a 5 N
force moves a block 4 m?
w=fxd
= 5N x 4m
= 20J



6. How much work is done when a 100
N force moves a block 59 m?
w=fxd
= 100N x 59m
= 5,900J
7. Fred applies 350 N of force to move
his stalled car 40 m, How much work did
Fred do?
 w=fxd
= 350N x 40m
= 14,000J



8. You move a 25 N object 5 m. How
much work did you do?
w=fxd
= 25N x 5m
= 125J


9. You carry a 20 N bag of dog food up a
6 m flight of stairs. How much work did
you do?
w=fxd
= 20N x 6m
= 120J

11. How far will 350 J raise a block
weighing 7 N?
Far = distance
 D = w ÷ f or D = w/f
 D = w/f
= 350J/7N
= 59m

12. How far will 350 J raise a block
weighing 15 N?
 D = w/f
= 350J/15N
= 23.33333333333333m
= 23.33m round to the nearest
hundredths



13. Which is more work, pushing with
115 N over 15 m or lifting 20 N 10 m?
w=fxd
w=fxd
= 115N x 15m
= 20N x 10m
= 1725J
= 200J
Pushing

14. Which is more work, pushing with
115 N over 15 m or lifting 200 N 10 m?
w=fxd
w=fxd
= 115N x 15m
= 200N x 10m
= 1725J
= 2000J
lifting
15. Write the units of force, distance,
work
 W= Joules (J)
 F = Newton (N)
 D= meter (m)
