In our everyday life we are surrounded by mechanisms. They help make our life easier in many ways. Most of the mechanisms you use are so familiar that you never think about them. Simple things like door handles, light switches, parts of a bicycle and a car are only a few examples. In the past, in old machines such as steam engines, the mechanisms were easy to see. Today they are hidden behind panels and covers. Mechanisms allow us to do simple things like switching on lights, running a bath and peddling up the hill easily on a bicycle. You will discover the uses of different mechanisms, as we look at them closer in this module.
Activity 1
Make a list of items that you think are examples of mechanisms? Sketches and pictures of these items can also be included.
LO 1.2
Mechanisms and Motion
Mechanisms can be used to change the speed, direction or force required to do something. Mechanisms may be able to help you but they cannot do it on their own. They need energy and someone or something to operate them. The energy that is used by a machine is called the input. The result of this energy input is called the output. A mechanism such as a bicycle can be explained with the diagram below.
Activity 2
Explain the advantages of sprockets and chains used in bicycles.
LO 2.3
Mechanisms are concerned with motion. There are four main types of motion. These can be illustrated by means of human body movements.
Activity 3
Name the type of motion illustrated by the products. Use arrows to indicate the direction of the motion.Product
Type of motion _________________Product
Type of motion ___________________Product
Type of motion ______________________Product
Type of motion ________________
LO 2.3
Types of mechanisms
Mechanisms are used in machinery. There are
five types of mechanism:
Levers enable forces to be applied at precise points.
Pulleys change the direction and speed of a movement, and allow the transmission of power.
Gears transmit rotary motion and force.
Cams and cranks convert uniform input motion to non-uniform output motion.
Screws allow rotary motion to transmit a linear force.
Activity 4
Answer the following questions based on the pictures A – F.
Name the mechanism in each of A - F.
Suggest a use for mechanism A.
In B, Axle 1 rotates at 10 rpm. How fast will axle 2 rotate?
To what use may mechanism C be put?
In D, if W rotates clockwise, how can you make V rotate anticlockwise?
Sketch a toy that could use mechanism F.
LO 2.3
Assessment
Learning outcomes(LOs)
LO 1
TECHNOLOGICAL PROCESSES AND SKILLS The learner will be able to apply technological processes and skills ethically and responsibly using appropriate information and communication technology.
Assessment standards(ASs)
We know this when the learner:
investigates:1.2 analyses existing products relevant to an identified problem, need or opportunity based on:
safety;
suitability of materials;
fitness for purpose;
cost;
manufacturing method;
LO 2
TECHNOLOGICAL KNOWLEDGE AND UNDERSTANDING The learner will be able to understand and apply relevant technological knowledge ethically and responsibly.
We know this when the learner:
systems and control:2.3 demonstrates knowledge and understanding of interacting mechanical systems and sub-systems by practical analysis and represents them using system diagrams:
gear systems;
belt drive pulley systems with more than one stage;
mechanical control mechanism (e.g. ratchet and pawl, cleats);
pneumatic or hydraulic systems that use restrictors;
one-way valves;
systems where mechanical, electrical or pneumatic or hydraulic systems are combined;
Memorandum
ACTIVITY 1
Learners could list any product that they regard as a mechanism. The aim of the activity is to help the learners to become aware of how many products actually are mechanisms. Discuss their examples in the classroom.
ACTIVITY 2
2.1 Greater forces can be transferred
2.2 Chains do not slip/slide
2.3 Chains can be unlinked to facilitate removal
ACTIVITY 3
Door handle Oscillating (handle) and backwards and forwards-movement (reciprocating)
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
from theory: distance [miles] = speed [mph] × time [hours]
info #1
speed_Dennis × 1.5 = speed_Wayne × 2
=> speed_Wayne = 0.75 × speed_Dennis (i)
info #2
speed_Dennis = speed_Wayne + 7 [mph] (ii)
use (i) in (ii) => [...]
speed_Dennis = 28 mph
speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5.
Substituting the first equation into the second:
W * 2 = (W + 7) * 1.5
W * 2 = W * 1.5 + 7 * 1.5
0.5 * W = 7 * 1.5
W = 7 * 3 or 21
W is 21
D = W + 7
D = 21 + 7
D = 28
Salma
Devon is 32 32 years older than his son, Milan. The sum of both their ages is 54 54. Using the variables d d and m m to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67.
Check:
Sales = 3542
Commission 12%=425.04
Pay = 500 + 425.04 = 925.04.
925.04 > 925.00
Munster
difference between rational and irrational numbers
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
