The velocity of a particle (v) at an instant t is given by $$v = at + b{t^2}$$ the dimension of b is

The Power $$(\mathrm{P})$$ radiated from an accelerated charged particle is given by $$\mathrm{P} \propto \frac{(q \mathrm{a})^{\mathrm{m}}}{\mathrm{c}^{\mathrm{n}}}$$ where $$\mathrm{q}$$ is the charge, $$\mathrm{a}$$ is the acceleration of the particle and $$\mathrm{c}$$ is speed of light in vacuum. From dimensional analysis, the value of $$m$$ and $$n$$ respectively, are

Which of the following quantity has the dimension of length ?

(h is Planck's constant, m is the mass of electron and c is the velocity of light)

In an experiment, the length of an object is measured to be 6.50 cm. This measured value can be written as 0.0650 m. The number of significant figures on 0.0650 m is