Question
Which one of the following equations of motion represents simple harmonic motion ?
(where, $$k,{k_0},{k_1}$$ and $$a$$ are all positive.)
A.
Acceleration $$ = - {k_0}x + {k_1}{x^2}$$
B.
Acceleration $$ = - k\left( {x + a} \right)$$
C.
Acceleration $$ = k\left( {x + a} \right)$$
D.
Acceleration $$ = kx$$
Answer :
Acceleration $$ = - k\left( {x + a} \right)$$
Solution :
As we know that, the condition for a body executing $$SHM$$ is $$F = - kx$$
$$\eqalign{
& {\text{So,}}\,a = \frac{F}{m} = - \frac{k}{m}x \cr
& {\text{or}}\,a = - {\omega ^2}x \cr
& {\text{Acceleration}} \propto - \left( {{\text{displacement}}} \right) \cr
& A \propto - y \cr
& A = - {\omega ^2}y \cr
& A = - \frac{k}{m}y \cr
& A = - ky \cr
& {\text{Here,}}\,y = x + a \cr
& \therefore {\text{Acceleration}} = - k\left( {x + a} \right) \cr} $$