The 49-g arrow is launched so that it hits and embeds in a 1.45 kg block. The block hangs from strings. After the arrow joins the block, they swing up so that they are 0.44 m higher than the block's starting point.

Required:
How fast was the arrow moving before it joined the block?

The arrow was moving at 16.2 m/s

Explanation:

The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:

where  is the mass of the arrow,  is the mass of the block,  of the change in height of the block after the collision, and  is the velocity of the arrow before it hit the block.

Solving for the velocity v, we get:

The arrow was moving at 16.2 m/s

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide

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 =