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## Homework Statement

a planet with radius of 12km spins at 520revs/s

find:

a) avg speed of a point on the planets equator over 2.5 of a revolution

b)find avg acceleration on stars circumfrance over 3/4 of a rev

c)find distance covered by point on the equator in 1 second

d) find displaement

f=520rev/s r=12000m

## Homework Equations

fc=mv^2/r

T=1/f

v=2piR/T

## The Attempt at a Solution

a) if i construct a vector triangle using v1 and v2 at the beginning of 3/2 of a rev and at the end, i can believe i can solve for vavg this way making a triangle where Vavg opposes the angle of 144 degrees...

v=2piR/T

where T=1/f

so i get v=2Pi*Rf

i considered V1and V2 = v

vavg^2 = 2(2Pi*R*f)^2-2(2Pi*R)^2cos144

is this okay?

b)m*ac=mv^2/R

where ac = centripetal accell

and v = 2pi*R*F

ac = ((2pi*R)*f)^2/R

c)m*ac= (d/t)^2/R

if t=1s

d=√(R*ac)

d)... i think i may have solved displacement above.. perhaps i am confusing the distance and displacement.