Question

An object moving in a straight line at constant speed A resultant force begins to act upon the object state the way in which the force may change the motion of object

Answer 1

According to the second Newton's law, the net force $\mathbf{F}$ should give some acceleration $\mathbf{a}$ to the object:

$$\mathbf{a} = \dfrac{\mathbf{F}}{m}$$

where $m$ is the mass of the object, and bold font denotes vector values. Since the object obtains acceleration, its motion changes the velocity magnitude or/and the velocity direction.

Answer. The velocity magnitude or/and the velocity direction chages.