With acceleration of 2500 m/s2, how long will it take to rreach speed of light

acceleration is change in velocity over time, or:

a = (v - v0)/t
where v = final velocity in m/s
v0 = initial velocity in m/s
t = time in s

assuming that it is initially at rest, v0 = 0,, the final velocity, v, is the speed of light, which is approximately 3.0 x 10^8 m/s
substituting:
2500 = (3.0x10^8 - 0)/t
now, solve for t.

hope this helps.