Which of the following quantities are always negative in a simple harmonic motion?

**For** **the** **motion** **to** **be** **simple** **Harmonic,** **Force** **must** **be** **linearly** **proportional** **to** **the** **displacement.**

*F* *=-kx*

*(a).* *=* *Cosθ*

*Direction* *of* *Force* *and* *acceleration* *is* *always* *same.* *Therefore,* *it* *will* *always* *be* *positive.*

*(b).*

*Direction* *of* *Velocity* *and* *displacement* *is* *always* *same;* *thus* *it* *is* *also* *coming* *positive.*

*(c).*

*Force* *is* *opposite* *to* *displacement.*

Dot product will become negative as for >90° ,is negative

So, this expression is negative

Again,

*(d)*

*Force* *is* *opposite* *to* *displacement* *so* *it* *will* *also* *be* *negative.*

*Therefore,* *Option* *(c).* *and* *(d)* *are* *correct.*

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