Question

the spin dryer of a washing machine rotating at 15r.p.s. slows down to 5 r.p.s after making 50 revolutons.find its angular acceleration​

Answer 1

Initial angular velocity, w1 = 15 rps = (15)(2π) rad/s

Initial angular velocity, w2 = 5 rps = (5)(2π) rad/s

Angular displacement, θ = 50 revolutions = (50)(2π) rad

Using,

w22 = w12 + 2αθ

=> α = -12.5 rad/s2

The negative sign indicates that the angular acceleration is directed opposite to the angular velocity.

Answer 2

Answer:

The angular acceleration is 3142 rad/s².

Explanation:

Given that,

Number of rotation $n_{1}=15 r.p.s$

Number of rotation $n_{2}=5 r.p.s$

After revolution 50

$t=\dfrac{1}{50}$

$t=0.02\ sec$

We need to calculate the angular acceleration

Using formula of angular acceleration

$\alpha=\dfrac{\omega_{2}-\omega_{1}}{t}$

$\alpha=\dfrac{2\pi n_{2}-2\pi n_{1}}{t}$

Put the value into the formula

$\alpha=\dfrac{2\pi\times(5-15)}{0.02}$

$\alpha=-3142\ rad/s^2$

Negative sign shows the deceleration.

Hence, The angular acceleration is 3142 rad/s².