Just like on a car, the brakes on the karts are very important to
slow you down. However, they are not just for stopping in emergencies.
They can also make your overall time around the course quicker!
This section investigates the brakes a little further.
When the kart is moving it has a type of energy called kinetic energy,
the faster it goes the more kinetic energy it has. This kinetic
energy is energy that you’ve given it from pedalling. If you
come to something on the track, or a corner, you may need to slow
down to avoid crashing. The kinetic energy that the kart has must
be transferred to another type of energy, which is what the brakes
will do.
Brakes convert the kinetic energy of the kart to heat energy –
they get warm when they are used. On a bicycle, the brake pads rub
against the wheel rims to slow it down. The harder the blocks are
pushed against the wheel, the bigger the force is and the quicker
the bicycle stops. The brakes need a large force to stop the bike
so we use a special mechanism or lever.
The force you can create by squeezing your thumb and fingers together
wouldn't be strong enough to stop a bike quickly. Therefore a mechanism
is used to multiply this force.
The picture below shows a right-hand brake lever.
The lever is fixed to the bike at a point called the pivot and
works in the same way as a seesaw. If you pull down on the right-hand
end with Force 1 then Force 2 is created pulling to the right.
Because the brake has a long handle, Force 2 is five times bigger
than Force 1. However, Force 1 must move five times the distance
that Force 2 moves. So the brake pads can apply a large force to
stop the bike, but don't move very far.
Try opening a door by pushing at the edge or near the hinges to
see how longer levers increase the effect of forces.
To stop the kart sliding or crashing it must go much slower round
the corners than along the straights. Without brakes, you would
have to travel at a near constant speed around the course, slow
enough to make every corner safely. With brakes you can speed along
the straights and then slow down for the corners. This is the faster
way to race, but tiring. Most of the energy you put into the pedals
ends up heating up the brake blocks!
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