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Hi for my mathematics investigation, I have been calculating the effect of velocity when the distance is extended. I have taken freefall into account and have used the Oregon state university to find an expression which correctly shows the velocity.

http://oregonstate.edu/instruct/mth252h/Bogley/w02/resist.html

However, I have found that my calculated value is much different to the value when I use the simple equation (distance/time). Are the calculations from this website wrong? and will I be penalised, or is distance over time an inaccurate representation?

Thanks, 

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2 hours ago, Ethan French said:

Hi for my mathematics investigation, I have been calculating the effect of velocity when the distance is extended. I have taken freefall into account and have used the Oregon state university to find an expression which correctly shows the velocity.

http://oregonstate.edu/instruct/mth252h/Bogley/w02/resist.html

However, I have found that my calculated value is much different to the value when I use the simple equation (distance/time). Are the calculations from this website wrong? and will I be penalised, or is distance over time an inaccurate representation?

Thanks, 

I believe that site did not have any wrong calculation. This is a very complicated Math SL IA (to be honest, I thought it was physics at first). 

If you have inaccurate representation, of course it won't deduct your mark for a lot because you attempted for this IA, the working is the most important part of marking. You should try to calculate again if you are free. However, if you get the same answer, go to your Math teacher and consult his / her advice.

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2 minutes ago, inriya said:

I believe that site did not have any wrong calculation. This is a very complicated Math SL IA (to be honest, I thought it was physics at first). 

If you have inaccurate representation, of course it won't deduct your mark for a lot because you attempted for this IA, the working is the most important part of marking. You should try to calculate again if you are free. However, if you get the same answer, go to your Math teacher and consult his / her advice.

Awesome! Thank you so much for your time!

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hi! I'm not sure I understood correctly, but if you are throwing an object (such as a ball) in freefall: 

when an object is freefalling, there are two forces acting on it

  • gravity (in the downwards direction);  (you might see it mention as the weight; this is mg, where m is the mass of the object and g is the acceleration due to gravity (9.8 m/s^2 ))
  • and air resistance (in the upwards direction) --> the faster the object is falling, the more air resistance there is, until the air resistance equals gravity (but in the opposite direction). This is when the falling object reaches a constant speed, also known as the terminal speed. 

But BEFORE the object reaches terminal speed, the forces are unbalanced (Gravity is stronger than air resistance); by newton's first law of motion, the object is accelerating (so its velocity is CHANGING). Since the velocity of the freefalling object is changing through most of its fall, the equation distance/time does not work. It gives you an average of the velocity over the whole path of the ball, but it does not give you the instantaneous velocity at a point. 

Hope this helped clarify your doubt!

 

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