Adentist's drill starts from rest. after 3.00 s of constant angular acceleration it turns at a rate of 2.90 ✕ 10^4 rev/min. (a) find the drill's angular acceleration. (b) determine the angle (in radians) through which the drill rotates during this period.

Initial angular velocity wi = 0

final angular velocity wf = 2.9 x 10⁴ rev/min

wf = 2.9 x 10⁴ (2*3.14 rad)/(60 sec)

wf = 3.035 x 10³ rad/sec

time t  = 3 sec

angular acceleration α

wf = wi + αt

3.035 x 10³ = 0 + α(3)

α = 1012 rad/s²

(b) angle covered is θ

θ = wi*t + (1/2)αt²

θ = 0*3  + (1/2)(1012)(3²)

θ = 4554 rad

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

b. a lightning bug, plug of grass, and a worm