If a rock is thrown upward on the planet mars with a velocity of 14 m/s, its height (in meters) after t seconds is given by h = 14t − 1.86t2. (a) find the velocity of the rock after two seconds.

 Velocity of rock after 2 seconds = 6.56 m/s

Explanation:

 We have equation of motion , , s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

Here height of rock in meters, h =

Comparing both the equations

    We will get initial velocity = 14 m/s(already given) and

     So,  Acceleration, a = -3.72

 Now we have equation of motion, v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration and t is the time taken.

 When time is 2 seconds we need to find final velocity.

     v = 14 - 3.72 * 2 = 6.56 m/s.

  So, Velocity of rock after 2 seconds = 6.56 m/s  

answer: a. same unit

explanation:

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 =