Unit D Flashcards
(16 cards)
What are the six simple machines?
The six simple machines are:
* Lever
* Inclined Plane
* Wheel and Axle
* Pulley
* Screw
* Wedge
What are the classes of levers?
The classes of levers include:
* First Class Lever:
- FULCURM is located in the center.
- Second Class Lever:
- LOAD is located in the center. - Third Class Lever:
- EFFORT is located in the center.
Each class is defined by the relative positions of the load, effort, and fulcrum.
What are the effects of a simple machines?
Name the 4 effects that can be obtained by using a simple machines. Give an example for each one.
- Increase the force:
- Example a Hammer - Increase the distance:
- Example a Ramp - Change the direction of the force:
- Example a Pulley - Transfer the force from one place to another:
- Example a Crowbar
What is a complex machines subsystems?
*Each subsystem contains a simple machine and usually has just one function.
*The bicycle is a good example of a complex machine. Several subsystems work together to move you forward at different speeds, allow you to turn, and help you stop.
Examples include transmission systems, linkages, and gears.
What is a complex machines systems?
A system is a group of parts that work
together to perform a function.
For example, the bicycle is a system for
moving a person.
What are linkages?
Transfers your energy from the pedals to the back wheel.
bikes
What is a transmission?
- Transfers your energy from the pedals to the back wheel.
- Transmissions Contains a number of different gears.
In a car, for example, the driver can select a low gear to start the car moving, and then change to higher gears when driving on a highway.
What are gears and how do they work?
A pair of wheels that have teeth that interlink.
Rotate together 🡪 transfers turning motion and force from one part of the machine to the other.
Pinion 🡪 a smaller gear (Y).
Driving gear 🡪 supplies the energy (X).
Driven gear 🡪 the gear to
which the force is directed (Y).
They are essential in many mechanical systems for altering force and speed.
What are the types of gears?
Pinion 🡪 a smaller gear (Y).
Driving gear 🡪 supplies the energy (X).
Driven gear 🡪 the gear to which the force is directed (Y).
How to solve for mechanical advantage?
Question: It takes 45 N to lift a 180 N box with a pulley. What is the machanical advantage of the pulley?
Question: It takes 45 N to lift a 180 N box with a pulley. What is the machanical advantage of the pulley?
Step 1) identify the information provided:
* Output force = 180 N
* input force = 45 N
Step 2) unkown variable:
* MA = ?
Step 3) correct equation:
* MA = F output/ F input
* F= force
Step 4) Manipulate the equation: (Already done)
Step 5) Subsitute the numbers:
* MA = 180 N / 45N = 4
Step 6) Calculate the equation:
* MA = 4
Step 7) Check your Units:
*N/N cancels out. MA in unitless
Final answer: MA = 4
MA = 4
- Mechanical Advantage (MA)= output force/ input force
- Force is meacured in newtons
- Output force = MA x Input force
- Input force= Output force/ MA
How to solve for Speed Ratio?
Question: It takes 6m of rope to lift a box 2m with a pulley. what is the speed ration of the pulley?
Question: It takes 6m of rope to lift a box 2m with a pulley. what is the speed ration of the pulley?
- input distance = this is how far the rope is pulled by the user (what you do)
- Output distance = this is how far the box moves (what the machine dose/ how much we get out of the machine)
- Input distance = 6m
- Output distance = 2m
Speed Ratio = INPUT/ OUTPUT= 6 / 2 = 3m
SR = 3m
- Speed Ratio (SR) = Input distance / Output distance
- Input distance=SR x Output distance
- Output distance = input distance/ SR
How to solve for Efficience?
Question 1: A pulley has a mechanical advantage of 5 and a speed ratio of 8. What is the efficiency?
Step 1: Idantify the given information
* MA = 5
* SR = 8
Step 2: Write down the formula
* Effeicience = (MA/SR) x 100
Step 3: Subsitute
* Efficience = (5/8) x 100
Step 4: Calculate
* (5/8) x 100 = 62.5%
Answer = 62.5%
Efficience = Mechanical advantage / Speed Ratio x 100
SR= MA x 100 / Efeicience
MA = Effeicience / 100 x Speed Ration
How to solve for work?
Calculate the work being done when a person pushes with a 50 N force for 3.5 m.
W = F x d
W = 50N x 3.5m = 175 J
Answer = 175 Joules
Work = force x distance (W x F= d)
work is used to calculate work input and work output
Efficience = Work Output / Work input x 100
work is measured in Joules (J)
How to Solve for work input and work output?
A pulley has an input force of 45 N, output force of 250 N, input distance of 8.0 m, and an output distance of 0.75 m. Calculate work efficiency.
Step 1 – Calculate work input:
* Work input = Force input × distance input = 45 N × 8.0 m = 360 J
Step 2 – Calculate work output:
* Work output = Force output × distance output = 250 N × 0.75 m = 187.5 J
Step 3 – Calculate efficiency:
* Efficiency = (Work output / Work input) × 100
= (187.5 J / 360 J) × 100 ≈ 52.08%
Answer: 52.08% efficient
How to solve for Work Efficience?
Efficiency is calculated as a percentage. So a machine that is 40% efficient loses more energy than one that is 70% efficient. You can calculate the efficiency of a machine by dividing its mechanical advantage by its speed ratio and multiplying the result by 100 (like we just did)
Another method we are now also going to use is:
* Efficiency (%) = (Work output / Work input) × 100
Hydraulics Formulas
Use a small force on the small piston to produce a larger force on the large piston.(p=F)
p =F/A
p = pressure (Pa)
F = Force (N)
A = Area (m2)
Measured in pascals (Pa)
1 Pascal is = 1 Newton over an area of 1 m2
