The tires of a car make 68 revolutions as the car reduces its speed uniformly from 85.0 km/h to 56.0 km/h. The tires have a diameter of 0.80 m.
a)What was the angular acceleration of the tires?
Express your answer using two significant figures.

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.

c)If the car continues to decelerate at this rate, how far does it go? Find the total distance.
Express your answer to three significant figures and include the appropriate units.

Respuesta :

a) The wheel of the car decelerates at an angular acceleration of - 0.577 radians per square second.

b) The wheel of the car requires a time of 51.149 seconds to stop.

c) The wheel of the car travels a distance of 683.225 meters before stopping.

How to analyze a decelerating rotating wheel

a) In this case we have a rotating wheel that decelerates at constant rate. The angular acceleration, in radians per square second, of the tires is determined by the following formula:

α = [ω'² - ω²] / (2 · θ)      (1)

Where:

  • ω - Initial angular velocity, in radians per second.
  • ω' - Final angular velocity, in radians per second.
  • θ - Change in the angular displacement, in radians.

The initial and final angular velocities, in radians per second, are now determined:

ω' = v' / R      (2)

ω = v / R      (3)

Where:

  • v - Initial linear velocity, in meters per second.
  • v' - Final linear velocity, in meters per second.
  • R - Radius of the tire, in meters.

If we know that R = 0.80 m, v = 23.611 m / s, v' = 15.556 m / s and θ ≈ 427.257 radians, then the angular acceleration of the tire is:

ω' = (15.556 m / s) / (0.80 m)

ω' = 19.445 rad / s

ω = (23.611 m / s) / (0.80 m)

ω = 29.513 rad / s

α = [(19.445 rad / s)² - (29.513 rad / s)²] / [2 · (427.257 rad)]

α = - 0.577 rad / s²

b) The time required to stop the car, in seconds, is determined by the following expression:

t = (ω' - ω) / α     (4)

t = (0 rad / s - 29.513 rad / s) / (- 0.577 rad / s²)

t = 51.149 s.

c) First, we find the change in angular displacement of the tire:

θ = [ω'² - ω²] / (2 · α)      (5)

θ = [(0 rad / s)² - (29.513 rad / s)²] / [2 · (- 0.577 rad / s²)]

θ = 754.781 rad

Lastly, the distance traveled by the vehicle is:

s = R · θ     (6)

s = (0.80 m) · (754.781 rad)

s = 683.825 m

To learn more on angular motion: https://brainly.com/question/14979994

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