InterviewSolution
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InterviewSolution
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A wheel which is initially at rest is subjected to a constant angular acceleration about its axis. It rotates through an angle of `15^@` in time `t` sec. Then how much it rotates in the next `2t` secA. `90^(@)`B. `120^(@)`C. `30^(@)`D. `45^(@)` |
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Answer» Correct Answer - B If angular acceleration is constant, we have `theta=omega_(0)t+(1)/(2)alphat^(2)` Given, `theta=15^(@), omega_(0)=0` For the 1st condition (time = t s) `15^(@)=(1)/(2) alphat^(2)`….(i) For the 2nd condition (time = 3t s) `theta_(1)=(1)/(2)alpha(3t)^(2)=(1)/(2)(alpha)9t^(2)`....(ii) So, the increase in angle through which it rotates in the next 2s, `Deltatheta=theta_(1)=(1)/(2)alphat^(2)` `=9xx(1)/(2)alphat^(2)-(1)/(2)alphat^(2)=8((1)/(2)alphat^(2))` `=8xx15^(@) =120^(@)` [from eq. (i)]. |
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