Author: Samuel Kwadwo Obeng
Co-Author: Nii Adjetey Sowah
Date: January 30, 2012
Task 1: Building your own machine
In the spirit of the African Cup of Nations, the purpose of your machine will be to get a small ball into a goal area, subject to some specified restrictions. Design and build a machine that can move the small ball provided from a resting position on the floor to a goal area at least 1 m away. The diameter of the ball is about 6 cm, and the dimensions of the goal area are 25 cm by 25 cm by 10 cm.
In this task, the main materials that my team used were:
2) Bathroom slippers
3) Khebab sticks
4) Electric Motors
6) Cello tape
We decided to design and build a machine that will pick up the ball, move to the goal area, and then drop the ball into the goal box. Given time constraints, we couldn’t build the machine to pick up the ball from the ground. However, when given the ball, the machine was able to move to the goal area and drop the ball into the goal box. Listed below are some simple machines that our machine was made up of:
2) Inclined plane
3) Wheel and axle
Two electric motors were used in the construction of this machine: one was used to power the machine to move, and the other was used in the pulley system (will be explained shortly). The electric motor that drove the machine was located at the rare of the system. It had an 8 tooth gear that drove a bigger gear of 16 teeth (1:2). The rationale behind allowing the small gear to drive the bigger one was to increase the torque and decrease the speed of the motor. The bigger gear was connected to an axle, which in turn connects to the two rare wheels. When the 9 volts battery was connected and the circuit closed, the back wheels rotated. The front wheels freely moved as a result of the push from the rare wheels. Sitting on the base of the machine were two piers made of cardboards. They both function as a lever and an inclined plane. A wedge-like cardboard, which carried the ball into the goal area, sat on top of the two piers. As a lever, the ball and the wedge-like cardboard container balances themselves on the edge of the tallest pier. When the car hits the goal box, the electric motor on the front of the car is triggered which pulls the string attached to the underside of the wedge-like cardboard. This board then slopes forward and rest on top of the shorter pier, functioning as an inclined plane. At this point the ball rolls down the inclined plane into the goal box.
Below is the sketch of the proposed machine.
The images below show the various parts of the machine after completion.
Fig 1.1: the wedge-like cardboard sitting on the two piers. At this point the machine functions as an inclined plane.
Fig. 1.2: The front view of the machine showing the front electric motor that support the pulley system
Fig 1.3: The wedge-like cardboard functioning itself as a lever on the tallest pier.