Concept
What is the difference between a physical system and social system?
Physical: parts and forces
Social: people & interactions
What is a system?
Group of individual parts that work together to complete a task
How much work is done if Barbie pushed a chair forward with a force of 2 N, and moved 10 m forward?
W = F x d
W = 2 N x 10 m
W = 20 Nm or J
Provide an example of a physical and social system
Physical: door handle
Social: school
How do you find a force, when you are given displacement and work? Write the equation.
F = W/d
Why has the food system changed from 1850 until now?
Society has changed
Concept: systems change because society changes
Any example of these changes is accepted.
What is a technological innovation?
An improved way of doing a task
A racoon carries garbage in its mouth with a force of 6 N, and walks to its home, covering a distance of 50 m. How much work was done?
Applied force is not in the same direction as distance, no work was done.
Provide an example of a technological innovation
Cellphone
True or False: the force of friction is in the opposite direction of the applied force
True - friction resists the applied force.
When is energy destroyed?
Concept: law of conservation of energy
The individual part
A force of 3 N is applied to a stapler. The stapler applies a force of 15 N to a paper. What is the mechanical advantage of the stapler?
MA = Output/Input
MA = 15 N / 3 N
MA = 5
Name 3 simple machines
Pulley, lever, wedge, inclined plane, screw, wheel & axle
Explain the how distance from the fulcrum affects force multiplication.
Farther effort (applied force) is from the fulcrum = more force multiplication.
When we calculate mechanical advantage, what does the answer tell us?
How many times the applied force was multiplied.
What is energy?
The ability to do work
A squirrel does 60 J of work by pushing a stick forward with a force of 12 N. How far did the squirrel travel?
D = W/F
D = 60 J / 12 N
D = 5 m
Which of the following are examples of kinetic energy?
Chemical, Sound, Light
Sound, Light
Where does force, work, and displacement appear in the design of a trebuchet?
Force: counterweight
Work: counterweight displacement
Displacement: rock launched from trebuchet, displacement of counterweight
Explain one way of how energy can leave a system.
Friction - contact between 2 surfaces speeds up particle movement and transfers kinetic energy to thermal energy (heat)
What is the difference between a process and mechanism?
Process: steps in a system
Mechanism: how each step works
A campfire has a total input energy of 2000 J. 1600 J is transferred to a pot as heat. Calculate the efficiency of the campfire.
Efficiency = (useful output energy / total input energy) x 100
Efficiency = (1600 J / 2000 J) x 100
Efficiency = 80 %
Write a mechanical advantage question where force multiplication does not happen.
Any question where the input force is greater than output force.
Name the purpose, inputs, process, and output of the school system.
Purpose: help youth learn
Input: teachers, students, curriculum
Process: classroom instruction
Output: smart children:)