Answer: Objects are attracted to each other due to the force of attraction (gravity). this force of attraction depends on the mass of the object. that is why your notebook is pulled towards you.
t is time in s For example, a car accelerates in 5 s from 25 m/s to 3 5m/s. Its velocity changes by 35 - 25 = 10 m/s. Therefore its acceleration is 10 ÷ 5 = 2 m/s2