Messing About in Boats - Rising Stars

Messing
MISSION FILE 3:15
about in
boats
My speed
boat is not vot
you’d call very
speedy.
There is a simple
explanation for that,
Blastov.
Ah! Thank
goodness. What
is it?
You have put the
outboard motor on
the wrong end!
36
TM
How does the shape of a boat change the way it moves?
Why do most boats have a pointed front?
Would another shape work as well?
Cut several small boats in different shapes from
expanded polystyrene or soft wood.
Push a cocktail stick mast into each boat. Put a paper
sail on each. Blow gently and see which moves through
the water most easily.

M1
Water resists objects moving through it.
Streamlining, smoothing and polishing the
objects will reduce their friction with the water.
Fix a thread to the front of each boat. Pull each
through the water.
How will you measure the pull force? Could you
use a thin elastic band?
Record the pull needed for each boat shape.
Aha! Zat is
better. Now let’s
see vot zis baby
can do!
Better untie it
from the mooring
first, Victor…
Da Vinci files
For many small animals,
swimming in water must be
like pushing though syrup;
and the same is true of some
small insects flying through
the air... How is it possible
that you could actually swim
faster through syrup than
through water?
ANALYSE
THIS!
Does the size
of its wheels
affect a
vehicle’s speed?
37

MISSION FILE 3:15
Messing about in boats
Mission title:
QCA scheme of work:
Resources:
Class organisation:
Messing about in boats
Unit 4D Solids, liquids and how they can be separated
Thread, paper, forcemeter, balsa wood or other floating material, Internet
access
Individual/group/class.
Knowledge review
Introducing the mission
Teacher’s notes
Further extension
for children
Useful websites
A streamline is a line that is parallel to the flow of water. Streamlined shapes
have sides that are as close to parallel to the flow of water as possible.
Animals and vehicles are said to be streamlined if their shape allows water
and/or air to move past them efficiently. Smooth sides reduce friction, sides
parallel to the air and/or water flow allow easy movement and a pointed front
end reduces the amount of resistance encountered by directing air and/or water
down the sides of the shape rather than against the front of it.
Swimming in syrup is as easy as swimming in water, even when the syrup is
twice as thick as water. This is because there is more thrust from pushing against
the thicker liquid and it cancels out the extra resistance the body encounters. The
test was carried out at the University of Minnesota. For tiny water animals,
swimming through water must be the equivalent of a human swimming through
syrup; yet they still make good progress.
Discuss how things move through water. Explain that the children are going to
investigate ways to make moving through water easier.
• Testing the boats could be messy – use a wet area or go outside.
• Make sure the boats are stable and have enough weight to sit in the water
while they are pulled.
• Think about different animals that live in water and work out how their body
shapes are adapted to help them move easily through the water.
• Does a streamlined shape for a paper plane mean that it flies further?
Investigate.
http://www.bbc.co.uk/schools/ks3bitesize/science/physics/forces_motion_8.shtml
describes what being streamlined means.
http://news.bbc.co.uk/1/hi/magazine/4801670.stm for more about swimming in
syrup.
Brain Academy Science Teachers Book 55