Question

The instantaneous angular position of a point on a rotating wheel is given by the equation . The torque on the wheel becomes zero at

• A. t = 1 s
• B. t = 0.5 s
• C. t = 0.25 s
• D. t = 2 s

Answer 1

Answer: (A)

t = 1 s

Answer 2

Given:

$\frac { \mathrm { d } ^ { 2 } \theta } { \mathrm { dt } ^ { 2 } } = 12 \mathrm { t } - 12$

Angular acceleration,

$\alpha = \frac { \mathrm { d } ^ { 2 } \theta } { \mathrm { dt } ^ { 2 } } = 12 \mathrm { t } - 12$

When angular acceleration ($\alpha$) is zero, then the torque on the wheel becomes zero ($\because \tau = \alpha$)

or t = 1 s