Good Science Victorian Curriculum Year 7

PHYSICAL SCIENCES: SCIENCE AS A HUMAN ENDEAVOUR
8.8
REDUCING THE
IMPACT OF
FORCES
LEARNING INTENTION
At the end of this lesson I will be
able to describe some examples
of technological developments
that have contributed to finding
solutions to reduce the impact
of forces in everyday life.
KEY TERMS
deform
to change shape
impact
the effect of a force
LITERACY LINK
SPEAKING
Pretend that your partner is
a student in primary school.
Explain to them how a crumple
zone works. Then swap roles,
with your partner explaining how
an airbag works.
NUMERACY LINK
GRAPHING
In a particular city, the
percentage of new cars sold
that had airbags was recorded
each year. The results were 18%
in 2006, 24% in 2007, 32% in 2008,
45% in 2009 and 60% in 2010.
Display this data in a line graph.
1
2
Many activities involve forces that can be uncomfortable,
painful or even harmful.
Engineers and scientists have developed products that can
reduce the impact of these forces. These products decrease
the forces we feel by absorbing them or spreading them over
a larger area.
Shoes can reduce forces on your feet
When was the last time you ran barefoot across dirt or gravel? All it takes
is landing on a pointy rock to remember to wear footwear next time!
Most footwear has a sole made out of some combination of rubber,
foam or other synthetic material. The design of these soles is meant to:
• provide grip, or traction, on a variety of surfaces
• reduce the force of impact from walking or running on a variety
of surfaces.
When you step on a pointy rock wearing shoes, the sole briefly
changes its shape – it deforms around the rock, spreading the contact
force over a greater area.
When you’re walking or running, the impact of the ground can be
evenly spread out across your foot, if your shoes are designed well
and fit you properly. Next time you put on your sports shoes, take
a look at how they’re designed. You should be able to see how the
design minimises the forces you feel when running.
How do shoes reduce the force of objects such as rocks?
Crumple zones absorb some impact
in car accidents
Vehicles let us travel much faster than we can on our own. This
increased speed comes with more risk. Why would you rather bump
into a wall while walking than when running? It’s because the forces
you experience are much greater at higher speeds than at lower ones.
If a modern car crashes into another object, its design means it will
deform. This reduces the forces on the driver and any passengers.
The front and rear of the car each have an area that is designed to
deform during a collision. This area is called a crumple zone.
How do crumple zones protect us? Think of it like running into a wall,
but this time you’re holding a cardboard box in front of you. The box will
be crushed first, absorbing some of the impact before it reaches you.
How does a crumple zone reduce the forces of a collision
on people in a car?
134 GOOD SCIENCE VICTORIAN CURRICULUM 7