Harry has two types of materials of the same mass, one is a piece of paper, the other a copper ball. (a) explain why the copper ball hits the ground first when both are dropped near the surface of the earth even if they experience the same gravitational acceleration.

In order to fall, both objects have to push the air out of their way so they can get by.  The copper ball is smaller, smoother, spherical, and streamlined.  The paper is bigger, rougher, flat, and a shape that doesn't slip and slide through anything too easily.  The force of air resistance, acting opposite to gravity and trying to hold the falling object up, is greater on the paper than on the copper ball.

If you could drop them in a place with no air, like in a vacuum chamber or on the Moon, they would hit the ground at the same time.

One of the Apollo astronauts ... I don't remember which one or which mission ... while he was on live video from the moon, took a feather and a hammer and dropped them at the same time.  Sure enough, they both hit the ground at the same time.

in physics zero. in muscle fatigue could be high

-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