Question

A weight of 20kg acts tangentially at a radius of 650 mm and causes a pulley to accelerate uniformly from 35 rev/min to 120 rev/min in 20 seconds. Calculate the work done and the average power required to cause this acceleration.

Clearly show the following values

wi=?

wf=?

θ=?

Torque=?

W=?

Pave=?

Answer 1

$W=20kg$

t=20 sec

actual air temprature Ta =$25\degree$

from the data

$h\alpha 0.8 V$

$h=k(0.8V)$

in the thermocouple read the radiation from the wall is proportional to $\Delta T$

$q_{radiation}$

$q_{radiation} = C(\Delta T)$

=C(Tb-Tw)

consider energy balance

$q_{conduction}$

$h\Delta T=C \Delta (Tb -Tw)$

$k(0.8V)\Delta T = C (Tb - Tw)$

from equation 1

$0.8 (5) k (25 - 50) = C (50 - Tw)$

$0.8 (10) k (25 - 40) = C (40 - Tw)$

$2/3 =(0.8) (5) k (-25) /(0.8)(10) k(15) = C (50 - Tw) / C ( 40 - Tw )$