Afemale orb spider has a mass of 0.55 g . she is suspended from a tree branch by a 1.2 m length of 0.0020-mm-diameter silk. spider silk has a density of 1300 kg/m3.
if you tap the branch and send a vibration down the thread, how long does it take to reach the spider?

Explanation:

Given Data

Mass= 0.55g = 0.00055 kg

length=1.2 m

diameter=0.0020 mm

density=1300

time=?

Solution

u is mass/length and F is tension

F(tension)=m*g

F=(0.00055)*(9.8)

F=

Mass per length(u) is given as

and for 1.2m length time is

so the answer is

the answer is false

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 =