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physics

 
 
Reply Thu 5 Sep, 2013 04:37 am
if im riding@80kph in my bike is my speed 80kph or less due to wind resistance
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Type: Question • Score: 6 • Views: 744 • Replies: 14
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fresco
 
  1  
Reply Thu 5 Sep, 2013 06:28 am
@blue train,
In general, air resistance decreases speed relative to the ground, but for the question to make sense, you need to state to what the 80kph is relative. You also need to state the magnitude and direction of the wind speed and to what those measurements are relative.
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timur
 
  1  
Reply Thu 5 Sep, 2013 06:59 am
Wikipedia wrote:
kph – a physical unit of speed or velocity (non-standard; km/h is usually preferred where SI conformance is important)
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gungasnake
 
  1  
Reply Thu 5 Sep, 2013 07:42 am
@blue train,
I you're doing 80, you're doing 80. Without the wind resistance (i.e. without the surrounding air), you'd die from asphyxiation and how fast you wre going would be the least of your problems...
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gungasnake
 
  1  
Reply Thu 5 Sep, 2013 07:44 am
@blue train,
A more realistic/meaningful question: If you're riding a bicycle along the top of a train at 20 kph and the train is moving at 80 kph (wrt the ground), how fast are you moving wrt the ground?? Answer is 100 kph...
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Lordyaswas
 
  2  
Reply Thu 5 Sep, 2013 07:47 am
@blue train,
blue train wrote:

if im riding@80kph in my bike is my speed 80kph or less due to wind resistance


Not enough information.

1. Has the rider been eating beans in the preceding 24 hours?
2. Is the bike motorised? Or can you move your legs really really quickly?
0 Replies
 
Setanta
 
  1  
Reply Thu 5 Sep, 2013 08:02 am
@blue train,
If you are riding at 80 km.p.h. on your bike, you are either one of the biggest liars who ever lived, or you have thighs the size of of a jumbo jet.
engineer
 
  1  
Reply Thu 5 Sep, 2013 08:05 am
@blue train,
If you are riding 80kph on your motorcycle, you are moving at 80kph. The air resistance only comes into effect if you need to determine the force required to move that speed.
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gungasnake
 
  -1  
Reply Thu 5 Sep, 2013 08:08 am
@Setanta,
Don't really grasp physics, do ya?? Past some point in thigh size, the whole process will stop and Mike Obunga or Hillary or whoever will just sit there on her bicycle wishing for smaller thighs...
Setanta
 
  2  
Reply Thu 5 Sep, 2013 08:10 am
@gungasnake,
Don't really grasp humor, do ya?
Lordyaswas
 
  2  
Reply Thu 5 Sep, 2013 08:15 am
@Setanta,
He can't grasp humour, but boy does he make me snort my coffee sometimes.

Hilarious.
0 Replies
 
Setanta
 
  2  
Reply Thu 5 Sep, 2013 08:16 am
Unintentional humor is always the best.
0 Replies
 
raprap
 
  1  
Reply Thu 5 Sep, 2013 11:39 pm
@blue train,
Speed is a scalar quantity, Velocity is a vector.

I can be speeding along at 80 km/hr--but my velocity will be 80 km/hr is 80 km/hr only if I traveling 80km/hr East on level ground.

Wind resistance is a Vector force that acts on a speeding body--but it's effect will depend upon the addiction of the vector

Rap
fresco
 
  1  
Reply Fri 6 Sep, 2013 12:06 am
@raprap,
Quote:
addiction of the vector

Laughing
raprap
 
  1  
Reply Fri 6 Sep, 2013 07:55 am
@fresco,
Post: # 5,431,552

Rap
0 Replies
 
 

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