For a rotating body

PHYSICS · Single correct · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion

Problem

For a rotating body, the angular displacement as a function of time is given by θ(t)=4t2−2t\theta(t)=4t^{2}-2t (in radians) for 0≤t≤3 s0\le t\le3\,\text{s}. Which of the following correctly states the angular acceleration and the direction of rotation at t=2.5 st=2.5\,\text{s}? (Take counter-clockwise as positive.) (a) The angular acceleration is +20 rad/s2+20\,\text{rad/s}^2, and the body is rotating counter-clockwise. (b) The angular acceleration is +8 rad/s2+8\,\text{rad/s}^2, and the body is rotating counter-clockwise. (c) The angular acceleration is +8 rad/s2+8\,\text{rad/s}^2, and the body is rotating clockwise. (d) The angular acceleration is −8 rad/s2-8\,\text{rad/s}^2, and the body is rotating counter-clockwise.

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