**Example 1: What is the force to be applied to a mass of 50 kg to produce an acceleration of 4 ms ^{-2} ?**

**Solution**

Here,

mass of the body, m = 50 kg

acceleration, a = 4 ms^{-2}

force, F= ?

**We know, F = ma **

=50 kg x 4ms^{-2}

= 200 kg ms^{-2} = 200 N

**Ans: 200 N**

**Example 2: A boy pushes a box of mass 20 kg with a force of 50 N. What will be the acceleration of the box?**

Here,

mass of the box, m = 20 kg

applied force, F= 50 N

acceleration of the box, a = ?

We know

**F = ma**

**a = F/ m = 50N/20kg = 2.5 ms ^{-2}**

**Ans: 2.5 ms ^{-2}**