This procedure has been used to "weigh" astronauts in space:
a 42.5 kg chair is attached to a spring and allowed to oscillate. when it is empty, the chair takes 1.30 s to make one complete vibration. but with an astronaut sitting in it, with her feet off the floor, the chair now takes 2.54 s for one cycle.
what is the mass of the astronaut?

Mass of astronaut will be 119.7674 kg

Explanation:

We have given mass of the chair

When there is chair alone then time period of osculation

Now when astronaut sit on the chair then total mass

Now with astronaut time period is

For spring time period is given by

So

Squaring both side

Mass of astronaut will be 119.7674 kg

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

-as effect of climate change started showing results, governments of various countries joined hands to fight against it, for which kyoto protocol was signed in japan in 1997, laid out emission targets for rich countries and required that they transfer funds and technology to developing countries, 184 countries have ratified it

hope this