A bus travel 400 m between 2 stops. It starts from rest and accelerates at 1.5 m / s ^ 2 until it reaches a speed of 5m / s. The bus continuous at this speed and then decelerates at 2 m / s ^ 2 until it comes to a stop. Find the total time required for the journey.

Explanation:

Time during which there was acceleration = (v - u)  / a = 5 / 1.5 = 3.33 s

Time during which there was deceleration = (v - u)  / a = 5 / 2 = 2.5 s

Distance travelled during acceleration = 1 /2 a x t² = 1/2 x 1.5 x 3.33²

= 8.32 m

Distance travelled during deceleration = 1 /2 a x t² = 1/2 x 2 x 2.5²

= 6.25 m

Total distance travelled = 400 m

distance travelled when the velocity was uniform = 400 - ( 6.25 + 8.32 )

= 385.43 m

uniform velocity = 5 m /s

time  during uniform velocity existed

= 385.43 / 5 = 77.1 s

Total time required in the journey = 77.1 + 3.33 + 2.5

= 82.93 s

labor day, patriot day, leaves start to change colors then fall from the tree

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.