The x and y coordinates of the particle at any time are x = 5t $$-$$ 2t² and y = 10t respectively, where x and y are in metres and t in seconds. The acceleration of the particle at t = 2 s is

In the given figure, a = 15 m s^$$-$$2 represents the total acceleration of particle moving in the clockwise direction in a circle of radius R = 2.5 m at a given instant of time. The speed of the particle is

If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is

A particle moves so that its position vector is given by $$\overrightarrow r = \cos \omega t\,\widehat x + \sin \,\omega t\,\widehat y,$$ where $$\omega $$ is a constant.

Which of the following is true?