MCQ
A wheel having a diameter of 3 m starts from rest and accelerates uniformly to an angular velocity of 210 r.p.m. in 5 seconds. Angular acceleration of the wheel is
- ✓$4.4 rad s ^{-2}$
- B$3.3 rad s ^{-2}$
- C$2.2 rad s ^{-2}$
- D$1.1 rad s ^{-2}$
✓
Answer
Correct option: A.
$4.4 rad s ^{-2}$
(A)
$n _1=0, n _2=210$ r.p.m. $=\frac{210}{60}$ r.p.s.
$d \omega=2 \pi\left( n _2- n _1\right)=2 \pi\left(\frac{210}{60}-0\right)=7 \pi rad / s$
$\alpha=\frac{ d \omega}{ dt }=\frac{2 \pi \times 210}{60 \times 5}=4.4 rad / s ^2$
$n _1=0, n _2=210$ r.p.m. $=\frac{210}{60}$ r.p.s.
$d \omega=2 \pi\left( n _2- n _1\right)=2 \pi\left(\frac{210}{60}-0\right)=7 \pi rad / s$
$\alpha=\frac{ d \omega}{ dt }=\frac{2 \pi \times 210}{60 \times 5}=4.4 rad / s ^2$
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