When the velocity of particle is 20 m/s then Distance travelled in 1 second = 20m Distance travelled in 1/20 second = 1m After covering 1m distance the velocity of particle become 25 m/s. It means, in 1/20 second, the velocity of particle increased by 5m/s. Thus acceleration a = ∆v/∆t = 5/(1/20) = 5×20 = 100 m/s²

a=(v-u)/t = 25-20/1 = 5 m/ s^2