When you look at a wheel spinning, a point near center of the wheel obviously goes around the center the same number of times that a point on the circumference. The point on the outside covers a larger distance than the point near the center. Does this mean that the point on the outside has a faster speed? I know that it must not be the case, but it is sure confusing to think about, the point in the center actually looks like it has the faster speed!
2006-08-17 05:43:29 · 8 answers · asked by Rick M 2 in Science & Mathematics ➔ Physics
There are two different velocities here: (1) Angular velocity - this is the rotational speed of the wheel which is the same no matter where along the radius of the wheel you are, and (2) Instantaneous linear velocity of a particular point along the radius, which is different depending where you are along the radius. The further away you are from the center of the wheel, the faster the linear velocity. That's why the center looks to be rotating slower.
2006-08-17 06:07:44 · answer #1 · answered by PhysicsDude 7 · 0⤊ 0⤋
Speed is a less precise word than velocity which is speed in a given direction; like 50 MPH due north. But speed is still a useful word when used with care. Both the hub and any point on the circumference have exactly the same rotational speed; such as 100 RPM. But a point on the hub a few inches from the axle and a point on the circumference have different linear speeds. Linear speed (or velocity) is along a straight line and it is confusing how that can apply to anything going around in a circle. In fact it is the speed along a tangent to the circle that lasts only an instant (like a high speed photo) and is the speed along a line if the point broke free and went straight ahead. The circumference has a much higher linear speed than the hub. This would be easy to see if the hub and the circumference were used to wind up two ropes, right? Hope that helps a little.
2006-08-17 14:41:45 · answer #2 · answered by Kes 7 · 0⤊ 0⤋
You are correct. The wheel turns faster on its rim than in its center.
Thereason why the center seems to go faster is that the eye can only process images up to a certain speed. When the speed gets higher, the eye sees a blur. The outer edge is moving very fast that it moves in a blur, so you really cannot see how fast it is spinning just by looking at it. The center, though, is spinning slowly, so you may see it spinning. The effect: an optical illusion that says the center is spinning faster.
2006-08-17 13:01:32 · answer #3 · answered by dennis_d_wurm 4 · 0⤊ 0⤋
Yes, the outer edge of the wheel is travelling at a faster speed than the centre. Have you ever seen a line of skaters or marchers as they turn a corner or spin around the middle person? The middle person is spinning very slowly but the people at the ends are moving very fast.
Think of this way too. If you were standing on the north or south axis point of the earth, you would be spinning in one spot every 24 hours, but someone at the equator would also be spinning around every 24 hours but they would have travelled 24,000 miles. Your speed is 0 miles per hour and theirs would be 1000 miles per hours.
2006-08-17 12:55:59 · answer #4 · answered by vmmhg 4 · 0⤊ 0⤋
Good question..
The further out you go from the center, the faster is the linear
speed of the circle..
Example:
Circumferance 2 inches from center may be 4 inches ( work with me here )...4 inches x 100 RPM will give you 400 linear inches of travel per minute..
Circumferance 4 inches from center may be 8 inches ..
8 inches x 100 RPM will give you 800 linear inches of travel
per minute..
RPM in both cases is the same..
A point on the 8 inch circumferance circle is traveling twice as
fast in a linear direction as the point on the 4 inch circle..
2006-08-17 13:12:00 · answer #5 · answered by Anonymous · 1⤊ 0⤋
when the wheel has both tranlatory and rotatory motion..the velocity of a point on the wheel is given by
V=v-rw
rotation is in the direction opposite to translation
where
V=apparnt velocity
v=velocity of translation
w=angular velocity of the wheel and
r=distance from the centre
...Hence the poinr on the circumferance exceeds the centre by a velocity rw where r is the radius of the wheel
---------------v+rw
0 ------- v
-------------------v-rw
the above is true for a wheel moving in anticlock wise direction......top part has velocity v+rw and the down part has v-rw velocity
2006-08-17 14:16:56 · answer #6 · answered by PIKACHU™ 3 · 0⤊ 0⤋
It is called angular velocity (Omega) and is measured as theta/t, where theta is the angle swept and t is the time taken. It IS faster compared to the inner circle / point
2006-08-17 12:57:12 · answer #7 · answered by PBVenkat 2 · 0⤊ 0⤋
it must move the same speed if it is one surface right? Are the point parralell to each other, does that matter?
2006-08-17 12:53:08 · answer #8 · answered by Anonymous · 0⤊ 0⤋