A shuttle bus slows down with an average acceleration of -2.4 m/s2. How long does it take the bus to slow from 9.0 m/s to rest?

Explanation:

Average acceleration is found by dividing the change in acceleration by the time.

The shuttle bus has an acceleration of -2.4 meters per square second. It slows from 9.0 meters per second to rest, or 0 meters per second. Therefore:

Substitute the values into the formula.

Solve the numerator.

We want to solve for t, the time. We have to isolate the variable. Let's cross multiply.

t is being multiplied by -2.4. The inverse of multiplication is division, so divide both sides by -2.4

It takes 3.75 seconds.

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.

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000