# Parachute Investigation

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• Published : March 1, 2013

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Research Question
How does the mass of the sandbag affect the amount of time the parachute takes to hit the ground?

Hypothesis
I predict that if the sandbag is lighter, the more time it will take for the parachute to reach the ground. The sail provides a drag pulling upwards to decrease the gravitational force that makes the sandbag fall, which is the mass times gravity. Thus, the lighter the sandbag, the less force there is pulling it downwards and, as a result, it travels slower and takes more time to reach the ground. According to Newton’s second law, F=ma, so as the mass gets lower both the acceleration and force will decrease.

Independent Variable
The independent variable is the weight of the sandbag. This variable will change in the experiment when we make different trials to test what weight of sand in the sandbag will make the parachute descend the slowest. The measuring device we will use is a scale and the unit of measurement is grams. I will 4 trials using 30 for the first 35g for the second trial, 45g for the third trial and 50g for the fourth trial.

Dependent Variable
The dependent variable will be the amount of time the parachute takes to hit the ground. This will be measured using a stopwatch. The units of measurement will be seconds.

Controlled Variables

Control Variable| Describe how you would keep this variable the same (controlled)| How is it measured andwith which measuringtool?| The length of the strings| I will keep this variable the same by measuring each string is equally the same by measuring 30cm (using a 1.2m string). If it weren’t controlled, the strings might get tangled up or the parachute will be tilted on one side and my results won’t be accurate| I will measure this by using a metre ruler| The height the parachute is dropped from| I will keep this variable the same by measuring and putting a mark where I will release the parachute. If it weren’t controlled, my results won’t be accurate because if I drop it higher, the time for the parachute to reach the ground will be different to if I drop it lower. The height will be 8.4 metres (4th floor to 2nd floor)| I will measure this by using a ruler and a marker.| The length and width (Area) of the sail| I will keep this variable the same by measuring 80cm by 70cm. If it weren’t controlled, the area of the sail will be different, thus affecting the drag of air and give different times of descend for parachute with the same weight. | I will measure this by using a metre ruler| Number of strings (4)| I will keep this variable the same by having 4 strings for each parachute. If it weren’t controlled, the strings might tangle up easily and my results will be inaccurate. | I will measure this by counting the number of strings|

Materials
* 1 80cm by 70cm Sail (Plastic bag)
* 4 strings-30cm each
* 1 pair of scissors
* Roll of Clear tape
* 1 Stopwatch/s
* Sandbag (1x 30g, 1x 35g, 1x 45g, 1x 50g)
* 1 Vivid (Marker)/Pen
* 1 Scale
* 1 meter Ruler

Method
1. Get a plastic bag around 85cm x 75cm or more and draw a line measuring 80cm by 70cm using a marker and cut it out, this will be the sail. 2. Fold the 4 corners measuring 3cm and make a small cut making a triangle hole which when you fold it back out again it will be a diamond shape. 3. Get strings the same length of 30cm each.

4. Get a sandbag of 30g, 35g, 45g and 50g
5. Tape all of the four strings onto to the holes in sail and tape them a few more times to be sure the strings are stable on the sail. 6. On the other side of the strings, tape all the strings altogether as one. 7. For the first trial, use a put 30g of sand into the sandbag. 8. Slot all the strings in the sandbag hole which is provided in the middle-top of the bag, then tape the strings a few times to make the strings secure on the sandbag, making sure all strings have a length of 30cm. 9. Now one parachute is finished....