A particle travels in a circle of radius 1.0 cm with a speed given...

The tangential acceleration of a particle in circular motion is given by the rate of change of its speed with respect to time.

Given the speed $v = 2.0 t$, the tangential acceleration $a_t$ is:

$a_t = \dfrac{dv}{dt}$

$a_t = \dfrac{d}{dt}(2.0 t) = 2.0 \text{ cm/s}^2$

Since the tangential acceleration is constant, its value at $t = 1 \text{ s}$ remains $2.0 \text{ cm/s}^2$.