Find out how a variable affects the terminal velocity of a parachute.

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Parachute Investigation

Aim

The aim of this investigation is to find out how a variable affects the terminal velocity of a parachute, and how it alters the speed that the parachute falls.

Theory

When an object falls in air, the air resistance opposing its motion increases as its speed rises, thus reducing its acceleration. Eventually, the air resistance acting upwards equals the weight of the object acting downwards. The resultant force on the object is therefore zero, since the two opposing forces are balanced. This is called terminal velocity.

Let us assume that the “explosion” image is the parachute. I will try to explain what happens as the parachute is released from a height.

  1. The parachute is released. The initial velocity is zero.
  2. The parachute starts to fall. The air resistance is small as the speed is small. The gravity remains the same.
  3. The parachute starts to speed up, thus increasing the air resistance. However, the gravity is still larger than the air resistance and the parachute continues to accelerate down.
  4. The parachute has accelerated to an optimum point where the air resistance and the gravity has reached terminal velocity, and the parachute reduces its rate of acceleration The parachute descends at a constant speed, as it has reached terminal velocity.

Variables

There are a few possible variables that would affect terminal velocity of a parachute:

  • The shape of the object, would affect the air resistance, depending on how smooth or rough the surface of the object is.
  • The surface area of the parachute, which is also the size of the parachute, would affect the air resistance acting on the parachute, which will affect the speed that the parachute falls.
  • The length of the string between the parachute and the object will affect how the parachute is spread out and ultimately determine how fast or slow it will reach terminal velocity.
  • The distance between where the parachute falls, and where it lands will affect whether terminal velocity is achieved or not.
  • The mass of the object would affect how fast the parachute would accelerate and achieve terminal velocity.
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Fair Test

To make sure that this experiment is a fair one, I shall be making all but one of the variable constant.

  • The shape of the object – Keeping it cubed-shaped throughout.
  • The surface area of the parachute – Keeping the parachute 50x50cm
  • The length of the string between the parachute and the object – Keeping the string length 30cm
  • The distance between where the parachute falls – Keeping it 2.65 meters

The only variable I am going to change is the mass of the object which is carried by the parachute. I am going ...

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