Sitting in a second story apartment a physicist notices a ball moving upwards just outside her window the ball is visible for 0.25 seconds as it moves a distance from the bottom to the top of the window. how much time does it take for the ball to reappear

The equation for the height h(t) of an object in free fall at time t with initial velocity v₀ and initial height h₀ is given by:

The change of the height(height of the window) h with time t=0.25s:

Solving for v₀, the velocity of the ball at the bottom of the window:

(i)

The equation for the velocity of an object in free fall with time T:

The moment the ball reaches the top of it's flight the velocity v=0:

(ii)

Setting equations (i) and (ii) equal and solving for T:

The time U it takes the ball to reappear is the difference between the flight time T and twice the time t it takes to cross the window.

-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

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