Question

If x denotes displacement in time t and x = a cos t, then acceleration is given by

• A. - a sin t
• B. a sin t
• C. a cos t
• D. - a cos t

Answer 1

Answer: (D)

Given displacement x = a cos t
$\therefore$ velocity $=v=\frac{dx}{dt}=a.-\sin t=-a\sin t$
$\Rightarrow v=-a\sin t$
$\because$ acceleration $a=\frac{dv}{dt}=-a\cos t$