18/09/2012

Abdelrahman Barakat

Selase Attah Kwamuar

Introduction:

The task is to build a machine. The purpose of the machine is to get a small ball into a goal area, subject to some specified restrictions. The machine should be able to move the small ball provided from a resting position on the floor to a goal area at least 1m away. The machine must have at least 4 steps (i.e. it must be made up of at least 4 simple machines). The diameter of the ball is about 6 cm and the dimensions of the goal area are about 25 cm x 25 cm x 10 cm.

Design Concept:

We started by brainstorming about how to get 4 simple machines to move a ball from a resting position to a goal area that is at least 1m away. We come up with a sketch that can move the ball from a resting position to another resting position. Figure 1 depicts the first sketch.

Figure 1

In figure 1 the simple machines includes a wheel, pulley, lever and incline plane. The purpose of these machines is to help with precision. We want to control errors as much as possible.  The rationale behind this concept is that we will put the ball on the left side of the lever and a load on the right side of the lever and then we tire a rope at the left side of the lever where we have the ball at a resting position in a container. With the help of the rope, wheel and the pulley we will pull the lever to an appropriate position. Once we release the rope, the lever propels the ball onto a resting plane and then the ball moves onto the incline plane onto another resting position.  Figure 2 depicts the machines that we added to it.

Figure 2.

As depicted in figure 2 we added another lever to the machine. The lever will propel the ball from its resting place to the goal area.

Implementation:

Below are the materials that we used to build the machine;

Plywood,

Ropes and strings,

Elastic (rubber band),

Pulley (office chair wheel),

Plastic bottles,

Nails,

Super glue,

Stones,

A candle,

Matches.

Figure 3 depicts the machine.

Figure 3.

Step 1

We started by sawing the plain plywood to get our inclined plane from it. We formed an incline plane by fabricating 4 rectangular plane. After that we created a resting plain that would hold the force of the ball. That was also fabricated by sawing 5 pieces of plains from the plywood.

Step 2

We created two levers. The lever comprises of a pivot, a load and an effort.  The pivot was made up from a wire mesh. The bar was made up from a long bar and the load from a stone.

Step 3

We drilled the pulley into the plywood that is holding the machine. We also put our wheel on a stand such that we could control how far the ball will be thrown away from the lever.  We then tied a string to the first lever through the pulley and finally to the wheel.

Step 4

The ball lands on an inclined plane which we made out of plywood. The inclined plane moves the ball to a second lever which works as a catapult.

Step 5

Our second lever has a cut bottle that holds the ball and a rubber band (elastic). This makes it possible for the ball to be catapulted to the goal area. We used a candle to trigger the release of the lever when a string is burnt.

Result:

The ball was able to move successfully 1m away from the machine to the goal area.

Conclusion:

The task is very challenging. The ideas were really not forth coming in the beginning but as we started implementing the ideas we got more ideas to make the machine work properly.