Question

The speed of a motor increases from $600rpm$ to $1200rpm$ in $20sec$. What is its angular acceleration and how many evolution does it make during this time.

Answer 1

$\omega ={\omega }_0+\alpha \times t$

for t=20sec or 1/3 minutes,

$\alpha =1800$

From ${\omega }^2={\omega }_0^2+2\alpha \theta$

$(1200{)}^2=(600{)}^2+2\times 1800\times \theta$
$1440000-360000=3600\theta$
$1080000=3600\theta$
$\theta =\frac{1080000}{3600}=300$