Please answer this question correctly! A 40.0 cm diameter disk rotates with a co

Question

Please answer this question correctly!

A 40.0 cm diameter disk rotates with a constant angular acceleration of 2.60 rad/s^2. It starts from rest at t 0, and a line drawn from the center of the disk to a point P on the rim of the disk makes an angle of 57.3 degree with the positive x-axis at this time. (a) At t = 2.34 s, find the angular speed of the wheel. Enter a number. differs from the correct answer by more than 10%. Double check your calculations. rad/s (b) At t = 2.34 s, find the magnitude of the linear velocity and tangential acceleration of P. linear velocity Your response differs from the correct answer by more than 10%. Double check your calculations. m/s tangential acceleration Your response differs from the correct answer by more than 10%. Double check your calculations. m/s2 (c) At t 2.34 s, find the position of P (in degrees, with respect to the positive x-axis). The response you submitted has the wrong sign counterclockwise from the +x-axis.

Explanation / Answer

(a)

angular speed w = w0 + alph*t

w = 0 + (2.6*2.34) = 6.08 rad/s

(b)

linear speed v = r*w

r = radius = 40/2 = 20 cm = 0.2 m

v = 0.2*6.08 = 1.22 m/s   <<<--------answer

tangential acceleration at = r*alpha = 0.2*2.6 = 0.52 m/s^2 <<<--------answer

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part(c)

theta =theta0 + wo*t + (1/2)*alpha*t^2

theta0 = 57.3 degrees = 57.3*(2pi/360) rad = 1 rad

theta = 1 + 0 + (1/2)*2.6*2.34^2 = 8.12 rad

theta = 8.12*(360/(2*pi)) - 360 = 465.24 - 360 = +105.24 degrees

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