Balls Fly Tying
 Krystal Glo Balls 10mm Fly Tying US $2.40 
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
Krystal Glo Balls 10mm Fly Tying US $2.40
|
 Krystal Glo Balls 7mm Fly Tying US $2.40
|
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
Krystal Glo Balls 7mm Fly Tying US $2.40
|
 Tungsten Beads 20mm 5 64 100pc Nickel Round Ball High Quality Fly Tying US $12.95
|
| Powered by phpBay Pro |
centripetal force question ; i've been given 3 examples of centripetal force but i'm a bit puzzled...?
examples;
1) the moon orbiting the earth
2) a ball attached to a piece of string tied to a pole, and the ball spinning around it
3) a man running around a circular track
i can see the connection between the moon orbiting the earth, and the ball attached to the string spinning around the pole; gravity is like the string; break the string, the ball flies off at a tangent; "switch off" the gravity, the moon flies off at a tangent
but i can't see how this relates to a man running around a circular track? there is no gravitational pull (from the centre of the track) and there is no "string" ?
The friction between the man & the ground provides the (inward) centripetal force to keep the man moving in a circle - like the tension in the string to the ball.
This is shown by how the man leans slightly toward the centre of the circle to avoid falling over. Imagine an upward vertical vector arrow is the reaction of the ground at his feet to his weight. The centripetal force by friction is a smaller arrow going inward. The vector total is these arrows added together. The man leans inward so his centre of mass & his feet are in line with the vector total arrow.
This is more obvious for a bike going round a bend.
| Powered by phpBay Pro |
