As a result of which it is possible to change the speed of the body?

Let’s write Newton’s 2 law in the following form: a = F / m, where a is the acceleration of the body, F is the force that acts on the body, m is the mass of the body.

Let’s write down the acceleration of the body: a = ΔV / t, where ΔV is the change in speed, t is time.

ΔV / t = F / m.

ΔV = F * t / m.

The formula shows that the reason for the change in the body’s velocity ΔV is the action of the force F.

The body changes its speed only under the influence of force.