4. A 65 kg woman is inside an elevator. Calculate her apparent weight (Normal Force) for the following cases: a. The elevator moves at constant speed of 10 m/s downward (2 pts)
b. The elevator accelerates upward at a constant rate of 2.4 m/s2 (2 pts)
c. If the scale read 450 N. Find the magnitude and direction of the elevator’s acceleration. (3 pts)

Explanation:

a ) Let her apparent weight be W₁

Net force on her = W₁ - mg

acceleration a = 0

W₁ - mg  = 0

W₁   =   mg = 65 x 9.8 = 637 N  

b )

a = 2.4 m /s²

W₁ - mg  = ma

W₁  = m(g + a )

= 65 x ( 9.8 + 2.4 )

= 793 N

c )

W₁ = 450 N

a = ?

W₁ - mg  = ma

450 - 65 x 9.8 = 65 x a

65 a = - 187

a = - 2.87 m /s²

acceleration is negative therefore , it must be downwards   .

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

-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