Secure httpselsession assignment ProblemID-77933061 BIOPHYS-1 231-002 Spring Sem

Question

Secure httpselsession assignment ProblemID-77933061 BIOPHYS-1 231-002 Spring Semester 2017 Chall HW Problem 8.22 Resource previous 3 of 7 next Problem 8.22 Part A What was the angular acceleration of the tires? The tires of a car make 90 revolutions as the car Express your answer using two significant figures. reduces its speed uniformly from 90.0 km/h to 64.0 km/h The tires have a diameter of 0.82 m a 1.62 rad/s? Submit My Answers Give Up Incorrect. Try Again: 3 attempts remaining Check your signs. Part B If the car continues to decelerate at this rate, how much more time is required for it to stop? Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

8.22 :

(A) r = 0.82 / 2 = 0.41 m

vi = 90 km/hr = 90 x 1000 m / 3600 s = 25 m/s
  
wi = vi/r = 60.96 rad/s

vf = 64 km/h = 17.78 m/s

wf = 17.78/ 0.41 = 43.36 rad/s

theta = 90 rev = 90 x 2pi = 565.49 rad

Applying wf^2 - wi^2 = 2 alpha theta

43.36^2 - 60.96^2 = 2 (alpha) (565.49)

alpha = -1.62 rad/s^2

(INclude minus sign also)

(b) Applying v = u + a t

a = alpha r = -0.666 m/s^2

0 = 17.78 - 0.666 t

t = 26.7 sec

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