Assertion :Velocity and acceleration of a particle in circular motion at some instant are: →v=(2^i)ms−1and→a=(−^i+2^j)ms−2, then radius of circle is 2 m. Reason: Speed of particle is decreasing at a rate of 1ms−2.
Hence, assertion is correct. Speed of the particle is decreasing due to a negative acceleration over x axis which has a magnitude of 1ms−2. Hence, reason is correct. But, radius of circle is calculated by using the radial acceleration and hence reason does not explain assertion in this case.