One way to get consistent, valid data is to:
be sure that instruments are calibrated properly.
use simple instruments to make measurements.
select the best data to place into data tables.
make the measurements as quickly as possible

Answer;

be sure that instruments are calibrated properly.

One way to get consistent, valid data is to be sure that instruments are calibrated properly.

Explanation;

In order for assessments or experiments to be sound, they must be free of bias and distortion. Reliability and validity are two concepts that are important for defining and measuring bias and distortion.

Reliability refers to the extent to which assessments are consistent. Another measure of reliability is the internal consistency of the items.

Validity refers to the accuracy of an assessment; whether or not it measures what it is supposed to measure.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.