What of the average speed from 4s from 8s
A.0.5m/s
B.1m/s
C.2m/s
D.3m/s
E.9m

Explanation:

At 4 seconds, the distance is 8 meters. Note the point (4,8)

At 8 seconds, the distance is 10 meters. The point here is (8,10)

Find the slope of the line through (4,8) and (8,10)

m = (y2-y1)/(x2-x1)

m = (10-8)/(8-4)

m = 2/4

m = 1/2

m = 0.5

The average speed on this interval is 0.5 m/s

Another way to look at it:

We've gone from 8 meters to 10 meters, so that's a change of y = 2 meters.

During this, the time has changed from 4 seconds to 8 seconds, which is a difference of x = 4 seconds.

The velocity is the rate of change of distance over time

velocity = (change in distance)/(change in time) = y/x = 2/4 = 0.5 m/s

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.