Mechanics 2 Coursework - 'woosh' down the slide

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Guowen Qin                                                                                                     2007-5-10

Mechanics 2 Coursework

‘woosh’ down the slide

Introduction:

The diagram below shows a slide. An object slides a distance L down the slide, and then shoots out at the end to fall through a vertical distance H before hitting the ground. Obviously, the greater L the further the horizontal distance D that it lands away from where it left the slide.

                                                                         L

                                                                           Ө

                                                                     

                                                          H            Plastic box

        

                                         D

To investigate how D is related to L for one particular angle of inclination, I am going

to do an experiment to see if this relationship turns out in practice to be as predicted.

The apparatus that is required is:

  • A Wood ramp(slope);
  • A Aluminium weight(cube);
  • A plastic box;
  • A piece of card board;
  • A meter rule;
  • A protractor

Before I do the experiment, I need to make some assumptions which are relating to both the model and the experiment:

When the experiment is conducted, it must be insured that all of the apparatus is attached securely to ensure that nothing comes apart. General laboratory rules must be recognised to ensure safety throughout.

The variable that will be investigated is the range that the object is projected.

The independent variable is the height up the slope that the block is released from. It is measured using a metre ruler.

The dependant variable is the distance from the slope in the horizontal direction that the block will travel.

When the object leave the slope, it might rotate then land on the ground. In fact, my calculation should consider the rotational energy of the object. However, this will make the calculation very complicated and it is beyond our syllabus, so the rotational energy has been ignored. To minimise this error, I need to be careful that do not use something will round along the slope or has strange shape.

To simplify this experiment, air resistance has been ignored as a factor in the range of the projectile. As it is a projectile(after leave the wood ramp) that will be measured, the only other factor working on it are gravitational forces. The horizontal motion of the projectile is independent of the vertical motion, and that is why the falling motion of the block does not need to be considered.

A aluminium block will be used, as it is a fairly dense object. This has benefits because although we are ignoring the effect of air resistance in the calculations, we should minimise the affect that it has. A lighter object, or one that has a larger surface area (i.e. is less dense), would show more affect from air resistance. I discussed with my group mates then decided to use a aluminium cube with dimension 3cm x 4cm x 5cm to do the experiment.

Unsure surface of the wood ramp, this is causing the fiction vary during the object is sliding down the slope or before sliding. Therefore, the work done against friction will vary. This will cause the most significant error in my experiment and I will explain why later.

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Energy transfer:

                                                                         L

                                                                           Ө

                                ...

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