Destinations humans have traveled in space

The transfer of heat through the movement of a gas or liquid a. convection b. conduction c. radiation

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

In an experiment, how can i change human errors? be specific.