Work
TRIPLE POINTS!
What is work? (Give the definition, formula AND units)
The amount of effort spent when a force causes an object to move a distance.
W = Force x Distance
Work is measured in JOULES (J)
TRIPLE POINTS
The parts that go into a system to make it function, such as energy, force, or raw materials.
INPUTS
Another word for an inclined plane is a...
RAMP
What is the formula for calculating mechanical advantage?
MA = Output Force / Input Force
TRIPLE POINTS!
If a garden is a natural physical system, then what is the process, inputs and outputs for it?
Process -> Photosynthesis
Inputs -> sunlight, water, fertilizer, seeds, Carbon Dioxide
Outputs -> anything that grows or comes out of it (plants, flowers, oxygen)
If you push something up a ramp with a force of 150N and it moves 2 meters. How much work is being done?
300 Joules of Work
W = f x d = 150 x 2 = 300
A set of connected parts that work together to perform a task.
SYSTEMS
TRIPLE POINTS
Which of the following is NOT one of the six simple machines?
a) Wheel and Axle
b) Magnet
c) Inclined Plane
d) Pulley
e) Screw
f) Lever
Magnet
DOUBLE POINTS!
Calculate the mechanical advantage when using a ramp to pull a box: 770 N weight, 110 N applied force.
The mechanical advantage is 7
MA = Output / Input = 770 / 110 = 7
If you are walking down the hallway while wearing your backpack you are...
a) Gaining a mechanical advantage by using your body as a simple machine
b) Doing work as you are applying force and moving a distance
c) Acting downward with gravity
d) None of the above
d) None of the above
Even though you're applying force (holding the backpack) and moving, the force you apply is upward while the motion is horizontal. Since work requires force in the same direction as motion, no scientific “work” is being done on the backpack.
Which scenario best explains why work is NOT done, even though a force is applied?
a) A student pushes a box across the floor and it moves forward
b) A person carries a heavy backpack while walking across a flat hallway
c) A student lifts a book straight up onto a shelf
d) A person pulls a sled forward across the snow
b) A person carries a heavy backpack while walking across a flat hallway
The force applied to hold the backpack is upward, while the motion is horizontal, which is not in the same DIRECTION!
DOUBLE POINTS!
The parts or results that are produced by a system, such as motion, heat, or finished products.
OUTPUTS
TRUE or FALSE
Simple machines reduce the amount of friction needed to do work in a system
FALSE
They reduce the amount of FORCE needed to make work and tasks easier. They often provide a mechanical advantage!
DOUBLE POINTS!
What happens if Mechanical advantage is greater than 1? What does the number mean?
The work becomes easier and the number represents how many times easier the task has become.
Using a ramp makes lifting an object easier because it decreases the ________, but increases the ________.
a) force required, distance over which the force is applied
b) distance, force required
c) work done, force required
d) gravity, mass of the object
a) force required, distance over which the force is applied
Calculate the amount of work being done for this scenario...
A construction worker uses a machine to lift a heavy load upwards. The machine applies a constant upward force of 820 N over a distance of 260 cm.
Work = Force x Distance
= 820 N x 2.6m
= 2132 J
Therefore, 2132 Joules of work is being done by the machine
Give 2 examples of a SOCIAL systems and 2 examples of a PHYSICAL systems
Answers vary...
Social = School, Hospital, Government
Physical = Car, Bicycle, Airplane, Human Body
DOUBLE POINTS
What is the name of the pivot point that that a lever rests on?
FULCRUM
Which scenario gives the greatest mechanical advantage?
a) LONG effort arm
b) LONG load arm
c) SHORT effort arm
d) SHORT load arm
a) LONG effort arm
BONUS (SELF DRIVING CARS)
List any four impacts of automated self driving cars which can affect people, society and the earth.
Economic → reduced labor costs; increased productivity and delivery speed, which means faster service for consumers
Social → job loss for drivers which affects the well being of their families; increased reliance or dependence on AI and technology which makes people lose their skills and creativity
Environmental → less gas pollution from larger delivery trucks and factories; and less drivers on the road which leads to fewer carbon emissions (which is good for the environment)