A grinding wheel, initially at rest, is rotated with constant angular acceleration of 7.36 rad/s 2 for 5.73 s. The wheel is then brought to rest with uniform deceleration in 8.37 rev. Find the angular acceleration required to bring the wheel to rest. Note that an increase in angular velocity is consistent with a positive angular acceleration. Answer in units of rad/s 2

Respuesta :

First calculate the wheel's angular velocity after having been accelerated:

ω = ω₀ + αt

ω = final angular velocity, ω₀ = initial angular velocity, α = angular acceleration, t = elapsed time

Given values:

ω₀ = 0rad/s (starts at rest), α = 7.36rad/s², t = 5.73s

Plug in and solve for ω:

ω = 0 + 7.36(5.73)

ω = 42.2rad/s

Then calculate the angular acceleration needed to bring the wheel to a rest in 8.37 revolutions. Use this equation for the wheel's rotational motion:

ω² = ω₀² + 2αθ

ω = final angular velocity, ω₀ = initial angular velocity, α = angular acceleration, θ = angle traveled

Given values:

ω = 0rad/s, ω₀ = 42.2rad/s, θ = 8.37rev = 8.37(2π)rad = 52.6rad

Plug in and solve for α:

0² = 42.2² + 2α(52.6)

α = -16.9rad/s²

The wheel must be decelerated at a rate of 16.9rad/s²

The angular acceleration required to bring the wheel to rest is -16.91 rad/s².

The given parameters;

  • angular acceleration of the wheel, a = 7.36 rad/s²
  • time of motion of the wheel, t = 5.73 s
  • number of turns made by the machine, θ = 8.37 rev

The initial angular velocity of the wheel when it started moving is calculated as;

[tex]\omega_i = \omega _0 + \alpha t\\\\\omega_i = 0 + 7.36 \times 5.73\\\\\omega_i = 42.17 \ rad/s[/tex]

The angular acceleration required to bring the wheel to rest is calculated by using third kinematic equation;

[tex]\omega _f^2 = \omega _i^2 + 2\alpha \theta[/tex]

when the wheel stops, the final angular velocity = 0

[tex]0 = (42.17)^2 + 2(8.37 \times 2\pi)\times \alpha\\\\0 = 1778.31 + 105.19 \alpha\\\\105.19 \alpha\ = - 1778.31\\\\\alpha = \frac{- 1778.31 }{105.19} \\\\\alpha = -16.91 \ rad/s^2[/tex]

Thus, the angular acceleration required to bring the wheel to rest is -16.91 rad/s².

Learn more here:https://brainly.com/question/11668123