Newton's second law expressed in terms of force and acceleration is [[1]]

Newton’s second law of motion states that “The force applied on a body is directly proportional to the rate of change of momentum ”. 

Let P₁ be the initial momentum of the body, m be the mass of the body, and u be the initial velocity.
Thus the initial momentum of the body is:
P₁ =mu

Let P₂ be the initial momentum of the body, m be the mass of the body, and v be the initial velocity.
Thus the initial momentum of the body is:
P₂ =mv

Change of momentum will be: P₂ - P₁ = mv - mu = m(v-u)

By Newton's second law of motion we know that:

Force = Rate of change of momentum

Force= $\frac{m(v-u)}{t}$

since acceleration(a) = $\frac{v-u}{t}$

Force = m a

Force will be equal to mass into acceleration.