Acar starts from rest and travels for 5.0 s with a uniform acceleration of +1.5m/s². the driver then applies the brakes, causing a uniform acceleration of -2.0 m/s². if the brakes are applied for 3.0 s, (a) how fast is the car going at the end of the braking period, and (b) how far has the car gone?

Part a)

Part b)

Explanation:

Part a)

Initial speed of the car = 0

acceleration of the car = 1.5 m/s^2

now at the end of t = 5 s the final speed of the car is given as

now after this car apply brakes which produce deceleration

so we have

time to during which deceleration is applied is given by

now we have

Part b)

distance moved by car during the period of acceleration of the car is given as

Now while car is decelerating then the distance moved by the car is given as

now total distance moved by the car

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =