A ball rolls at a constant 100 feet per minute as it approaches a hill. It then rolls down the hill gaining speed. At the bottom of the hill, it is going at 300 feet per minute. If it took 2 minutes to roll down the hill, then what is the distance from the top of the hill to the bottom of the hill?

a = (Vf - Vi) / t

a = (300 ft/min - 100 ft/min) / 2 min = 100 ft / min^2

2 a s = Vf^2 - Vi^2

s = (Vf^2 - Vi)^2 / (2 * a)

s = (9 - 1) * 100^2 / 200 = 800 / 2 = 400 ft      length of hill

a.   mass number from atomic number

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.