Machine?
What is a machine?
A device that makes work easier.
How do you find mechanical advantage?
Output Force divided by Input Force
MA= Fout/Fin
What is the number that tells you how many times a machine multiplies force?
Mechanical Advantage
What is the mechanical advantage if you use 70N to make a machine exert 245N?
MA= Fout/Fin
= 245N/70N
= 3.5
The result when a force moves an object a certain distance
Work
What are the three ways a machine can make work easier?
Provide an example for each Bonus (300 points)
1. Increasing the force applied. (e.g. carjack or nutcracker)
2. Changing the direction of the force. (e.g. elevator or pully for the blinds)
3. Increasing the distance over which force is applied (e.g. a ramp or staircase)
Which is better, a machine with a mechanical advantage of 3 or 8?
8
A group of parts that work together to perform a specific task.
A system
Fours friends each apply 50N of force to move a table 12m.
How much work was done on the table?
2400 j
The ratio of output force to input force
Mechanical Advantage
What are three examples of machines?
Scissors, knife, screwdriver, pencil sharpener, car,...
If you push with 20N to move a 300N desk up a ramp, what is the mechanical advantage of the ramp?
300/20 = 15
A group of physical parts that work together to perform a specific task.
Provide an example (Bonus 100 points)
Physical System
Computer or solar system
What is the formula for work?
Suppose Clara pushes a box with a force of 150N and moves it 5 m. How much does the box move?
W=Fd
= 150N x 5m
=750 J
What is the metric unit for force?
Who is it named after and why? (Bonus 200 points)
Newton (N)
Since weight is the force of gravity, it is named after Sir Issac Newton
True or False:
Machines increase the amount of work done
False
What are the units for mechanical advantage?
There are no units
A group of people who join together to accomplish certain tasks.
Provide an Example (Bonus 100 points)
Social System
School system or ant colony
Machine A uses 40N of force when you push with 30N. Machine B uses 50N of force when you push with 40N. Which machine has a better mechanical advantage?
Machine A has a better mechanical advantage of 40/30 = 1.33
While Machine B = 50/40 = 1.25
___________ is the force that opposes the relative motion of an object.
Provide an example.
Friction
Rubbing your hands together creates thermal energy because it is resisting the force
How does a machine lower the amount of the force needed?
Increasing the distance
What does it mean if the mechanical advantage is less than one?
Provide an Example (Bonus 100 points)
The machine lowers the force and increases the distance.
For example, a hockey stick hitting a puck
What are the two types of force? Provide an Example of each.
Contact Force - kicking a soccer ball
Action at a distance - gravity pulls an object to the ground
A Pulley system takes a force of 50N to raise a 20N textbook 2m off the ground.
What is the efficiency of the pulley system?
40%
What are the 2 categories of energy?
Provide an example for each.
Kinetic energy - is when the object is in motion (moving car)
Potential energy - when energy is stored in an object (stretching a rubber band)