The Factors Affecting the Stopping Distance of a Margarine Tub

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The Factors Affecting the Stopping Distance of a Margarine Tub

Aim:

To investigate the factors that affect the stopping distance of a

catapulted margarine tub. In this experiment, I will be concentrating

on the effect that varying the mass of the catapulted tub has on its

stopping distance (sd.).

Introduction:

Things that move eventually have to stop. However, where they stop

depends on several factors- their mass (the mass of the moving

object), the speed the moving object is going at, the friction between

the surfaces and the air (or water) resistance and movement around the

object. The stopping distance (or sd.) of an object is how far it

travels before stopping.

As an object moves forwards, it has kinetic energy (KE) pushing it.

However, as it moves, it also creates friction. This changes the KE

(kinetic energy) of the moving object into heat energy. This means

that there is less KE and more friction. The forces become unbalanced

as more and more of the KE is transformed into heat energy. The force

pushing the object forwards is then less than the force pushing it

back, so the tub stops moving. The larger the force of friction acting

on the object, the faster it loses speed.

The type of surface that the catapulted margarine tub (or any moving

object) is moving along also affects the amount of friction that acts

on the object. A very smooth surface - for example, a mirror- would

create much less friction than a very rough surface- for example,

sandpaper. This in its turn would also affect the sd. of the tub- for

a smooth surface, the stopping distance would have lengthened, and for

a rough surface, the sd. would be shortened.

If a margarine tub uses a stretched elastic band to catapult it

forwards, then the amount the elastic is pulled back determines how

far the object travels before stopping. When the elastic band is

pulled back then it has Elastic Potential Energy (EPE) which is

changed to kinetic energy (KE) when the band is released.

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