Q.

The oscillation of a body on a smooth horizontal surface is represented by the equation, X=Acos(ωt)

where X = displacement at time t

          ω = frequency of oscillation

Which one of the following graphs shows correctly the variation of a with t  

Here a = acceleration at time t, T = time period                                                                [2014]

1  
2  
3  
4  

Ans.

(3)

Here, X=Acosωt

    Velocity, v=dXdt=ddt(Acosωt)=-Aωsinωt

Acceleration, a=dvdt=ddt(-Aωsinωt)=-Aω2cosωt

Hence the variation of a with t is correctly shown by graph (3).