In an experiment, you test whether the number of times you rub a cloth against a balloon changes how long it will stick against the wall. You start by rubbing the balloon 10 times with the cloth and stick it to the wall. You repeat this three times and record your results in a table. Observation
Number of Times Balloon is Rubbed by Cloth Trial #1 Trial #2 Trial #3
10 6 seconds 20 seconds 20 seconds
What statement best reflects why you should do repeated trials in an experiment? (2 points)

a
Rubbing the balloon against a cloth 10 times produces very different results each time it is repeated.

b
The first trial is right because it is done with new materials that give the best results.

c
The second and third trials were wrong because they were very different from the first trial.

d
You would make a wrong conclusion if it were based on the first trial in the experiment.

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.

a 2,000 calorie based diet.