How long does it a take a runner, starting from rest to reach max speed, 30 f/s given acceleration 8 f/s^2? after finding the time, calculate the distance traveled in that time.

Explanation:

Given that,

Initial sped of the runner, u = 0

Final speed of the runner, v = 30 ft/s

Acceleration of the runner,

Let t is the time taken by the runner. It can be calculated using first equation of motion as :

t = 3.75 seconds

Let s is the distance covered by the runner. Using the second equation of motion as :

s = 56.25 feet

Hence, this is the required solution.

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.

option number c is the right answer.