Yr. 12 Physics Assessment Task #1: Part A
Open ended investigation By Rex Whiticker
The Project motion of a catapult being fired is varied by a range of factors that affect the path of the projectile. In this experiment, the angle of trajectory, mass of the projectile and change in initial velocity of the launch, were all factors considered in the end result to investigate the properties of projectile motion. The purpose of the experiment was to conduct a first-hand investigation to design and analysis how angle, weight and power affect projectile motion, collecting approximate values and recording results.
Parabolic motion has been studied for a long time dating all the way back to the time in which Galileo was conducting experiments. During the experiment two angles were fired at 320 and 100 at two different power levels and weights.
Galileo was the first person who accurately described projectile motion. Because of the drawings of Niccolo Tartaglia, Galileo realized that a projectile followed a curved path which is called a parabola. The parabola had an exact mathematical shape that was acted upon two forces, vertical and horizontal. His experiments included rolling balls down a highly polished inclined plane (to lower the acceleration) and record similarities. His work showed that horizontal motion experinces no acceleration and vertical motion is affected by gravity (9.8ms-1). Aim: Compare factors that influence the trajectory in a project motion experiement through altering angle, weight and power. Hypothesis: The marble analyzing weight, four rubber bands comparing power and 10o angle will reach the greatest distances.
* * Elastic bands
* Band saw
* Power Drill
* 1 inch drill bit
* 1/2 inch drill bit
* Wire coat hanger x 1
* Blutac (optional)
* Small Screws x 16
* Tiny screw x1
* Milk bottle top
* 5 of 14.5cm Hard wood
* 2 of 25cm Hard wood
* 1 of 20cm Hard wood
* 2 of flat board pieces in the shape of a square but cut diagonally across was a square 14x9cm Hard wood. Cut out the square then cut it diagonally so it is in two parts (Fig 1)
Fig 3: end result
Fig 1: cutting triangles
Fig 2: green ball (1.8g)
* Soft balls (2cm radius)
* Marbles (1.5cm radius)
* Video recording device with slow motion reply (iPod app) * Books to help angle the catapalt
* Safety glasses
* Tape measure
* Meter ruler
* Sticky tape
* When using the power tools, have a parent on stand by and supervision * If you do not own a Work place and safety card (from wood work-yr.10) DO NOT use the band saw to cut the peices of wood. Get your parents to do it
Making the catapult:
1. Arragnge the two of the 25cm pieces and two of the 14.5cm pieces as shown in the picture
2. Now add the triangular pieces and either nail, screw or glue them down just as shown. Note that these two pieces you have made are not identical. They are actually mirror images.
3. Stand the two pieces you just made up on two 25cm pieces as shown. Then screw and glue end sections and with the power drill, drill thin pilot holes. This will help prevent cracking of the wood. A pilot hole is just a thin hole , usually around 1/8 inch that goes right through both pieces of wood where you are going to put the screw or nail.
4. Now install the crossbar at the top of the uprights. Repeat the procedure of the pilot holes using the power drill and screw it as close to the top as possible.
5. Now we need to drill three holes. The picture below shows where to drill. All of the holes should be exactly straight in line with each other using the 1 inch drill bit. After doing this, cut and feed the straight section of the coat hanger with the 25cm piece of wood in the...
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