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