2nd grade (E.S.O.) UNIT 2: STRUCTURES & MECHANISMS (CLASS ACTIVITIES)
1 NAME AND SURNAMES:
2 NAME AND SURNAMES:
Group:
/Date Signatures Day/Date Signatures
1/ Name1: Name2:
2/ Name1: Name2:
1. Which of the following objects (plasticine, T-shirt, casing, kneepad and paint) is a
structure? Identify them and put a on those which are structures.
Structures and functions:
1: support a load 2: span a gap 3: protect an object 4: provide rigidity
2. Classify the following structures into the correct group according to their function:
armoured vehicle car bumper egg carton bulletproof vest
car cable motorcycle helmet kneepad scaffold
• Supporting loads:
• Spanning gaps:
• Protecting objects:
• Providing rigidity to objects:
3. Indicate the name of the structures below and the principal material they are made of
(materials: wood, marble, steel, concrete, carbon fibre, stone, aluminium, bone):
Guggenheim Museum
titanium covering (sheets)
Taj Mahal
carbon fibre, fibreglass
and
bicycle frame
bones
______ and steel
scaffold
cable car
__________ cables
4. EXTRA. Structures: definition and types. Fill in the blanks with the following words:
natural, tunnels, cases, rigid, collapse, frames, bridges, resist, stable, artificial, deformed,
lightweight, fulfil, skeleton and shells.
A structure is a ____________ object with a definite size and shape, which purpose is to
____________ forces without changing its shape or size (becoming ____________).
Structures can be divided into two groups according to their origin: ____________ and
____________ (manufactured) structures. Examples of natural structures are the
____________ of a human being, rocks, trees, coral reefs, ____________ and birds' nets.
Examples of manufactured structures are: ____________ (suspension bridges, arch
bridge, beam bridge …), ____________, buildings, ____________ of objects (computers,
mobile phones, etc.), airplanes, picture ____________ … Designers know that structures
must ____________ (meet) 3 important structural conditions: resistance (the capacity
to bear or withstand external forces without breaking), rigidity (rigid enough to
keep its shape when a force is applied to it) and stability (____________ to remain
upright and not topple (fall) or ____________ when a force acts on it). In addition to
this, modern structures must be ____________ (not heavy).
5. Stresses. Identify the different stresses that structures can be subject to and
indicate the probable effects on them:
compression
Effect:
Effect:
Effect:
Effect:
Effect:
6. Identify the principal stresses in the images below:
Stress: Stress: Stress:
Stress: Stress: Stress:
Stress: Stress: Stress:
1: 2: 3: 14: 15:
4: 5: 16: 17:
7. Strong shapes (arches, triangulation and sections). Identify the shapes below:
8. Triangulation. Draw the stresses that triangle T is subjected to and make the minimum
triangulation in the rest of the figures (the last one has several triangulations).
T
9. Draw three solutions to stiffen (strengthen) the deck of the bridge below indicating
the name of the structural elements added:
10. Identify and classify the structures below into the correct group (mass, vaulted,
frame, triangulated, suspended, shell, geodesic and pneumatic structures)
Wall, mass
Bottle, shell
Day /Date Signatures Day/Date Signatures
3/ Name1: Name2:
4/ Name1: Name2:
What is a machine for?
1. Read the text above and complete the activities:
A machine is a device that makes work easier. Machines allow humans to do many things that
would otherwise be impossible. Machines use energy to help us do work.
But what do we mean by work? In science, work is done whenever an object is moved over a
distance. To move something, you must use force. The more force it takes to move an object, the
more work is done. The greater the distance the object moves, the greater the amount of work it
takes to move it. A machine can make work easier in three ways. It can change the size of a force,
the distance the force acts or the direction of a force.
a. Label each picture below with one of the ways a machine can make work:
The force you apply to a machine is called the effort (applied force or input force). The force a
machine supplies is called the output force. The object moved by the output is called the load.
b. Label the machines below with the words: input force (effort), output force and load.
Now complete the text below by filling in the blanks with word from the original text:
c. A machine is a ______ that makes work______. Machines also allow humans to do
many things that would otherwise be________.
d. Machines can make work easier in three ways. A machine can change the magnitude
(_____) of the force you apply, the _______ the force acts and the ________ of the
force.
e. The force you apply to a machine is called the ________ (applied force or ________
force). The force a machine supplies is called the ________ force. The object moved by
the output is called the________.
2. Simple Machines.
A simple machine is a machine that uses only one movement and it is with few or no moving parts.
A compound machine is a combination of simple machines. There are six kinds of simple machines.
Each one has a special way of making a force stronger. The six simple machines are as follows:
inclined plane, wedge, screw, lever, and wheel and axle, and pulley.
Identify, in the compound machines below, the 2 or 3 simple machines they are based on:
3. Types of motion. Identify in the machines below the type of motion they produce
(rotary motion, linear motion, reciprocating motion and oscillating motion):
See-saw: Conveyor belt: Piston:
Cam: Sliding gate: Electric Motor:
Pulley: Needle of a sewing
machine: Pedal: Windscreen wiper:
Rack (rack and pinion): Piston in a car engine:
4. Mechanisms. Read the text below and answer the questions:
A mechanism is an arrangement of connected parts (set of rigid components) working together
and that are designed to perform (do) a particular function in order to transmit and convert
forces and motions.
• Name of the mechanism:
• 3 rigid components:
• Input: number and type of motion: 1, rotary
• Name of the machine (object):
• Function (work):
• Transmission element:
• Output: number and type of motion: • Chain (type of motion):
5. Answer the questions about the mechanism below:
• Name of the mechanism:
• 3 rigid components:
• Input: number and type of motion:
• Output: number and type of motion:
• Transmission element:
• Input speed:
• Output speed: <100, =100 or >100?
6. Indicate in the mechanisms below the input (I), the output (O) and input and output
motions
reciprocating-rotary
7. Indicate, in the mechanisms below, the direction of rotation of the input (driver) and
the output (driven) and whether (if) the speed of rotation on the driven is increased, is
reduced or does not change:
anticlockwise- anticlockwise
speed is reduced
8. Complete the table below about mechanisms:
rpm stands for: : :
A synonym of velocity is: : :
gear train