Bob and Lily are riding on a merry-go-round. Bob rides a horse on the outer edge of the circular platform and Lily rides a horse near the center. When the merry-go-round is rotating at a constant angular speed w, Bob's speed isa) exactly half as much as Lily'sb) exactly twice as much as Lily'sc) smaller than Lily'sd) larger than Lily'se) same as Lily's

Respuesta :

Answer:

d) larger than Lily's

Explanation:

If the merry-go-round is rotating at a constant angular speed, this means that any two points, located at different positions along a radius, rotate at the same angular speed, which means that they sweep the same angle at a given time interval.

In order to both points keep aligned along the same radius, we have a single choice (assuming that we are talking about a rigid  body) to meet this premise:

The point farther of the center (Bob) must have a linear speed greater than a point closer to the center (Lily).

Mathematically, we can explain this result as follows:

ω = Δθ / Δt (by definition of angular velocity) (1)

but, by definition of angle, we can say the following:

θ = s/r , where s is the arc along the circumference, and r, the radius.

⇒Δθ = Δs /r

Replacing in (1) we have:

ω = (Δs /Δt) / r

By definition, Δs/Δt = v, so, arranging terms, we get:

v = ω*r

If ω=constant, if r increases, v increases.

So, as Bob is at a distance r from the center larger than Lily's, Bob's speed must be larger than Lily's.