Question

A 10n force acting on a certain mass increases its speed uniformly from 0 to 25 m/s in 5s. The magnitude of the mass in kg is?

Answer 1

The acceleration of an object

$$a=\frac{\Delta v}{\Delta t}=\frac{25}{5}=5\:\rm m/s^2.$$

The mass of an object

$$m=\frac{F}{a}=\frac{10}{5}=2\:\rm kg.$$