Obtain the differential equation of linear simple harmonic motion.
For simple harmonic motion (SHM), the restoring force is proportional to the displacement \( x \) from the equilibrium position:
\[ F = -kx \] By Newton's second law, \( F = ma \), where \( a \) is the acceleration. Therefore, we have:
\[ ma = -kx \] Since acceleration \( a = \frac{d^2x}{dt^2} \), the equation becomes:
\[ m \frac{d^2x}{dt^2} = -kx \] This is the differential equation of SHM, which can be written as:
\[ \frac{d^2x}{dt^2} + \frac{k}{m} x = 0 \]
Derive an expression for maximum speed of a vehicle moving along a horizontal circular track.
If the mean and variance of a binomial distribution are \( 18 \) and \( 12 \) respectively, then the value of \( n \) is __________.