Three children are struggling and pulling on a single toy. Two of the children, Abe and Barry, are EACH (individually) pulling with a force of 60 Newtons. The third child, Eric, is pulling with enough force to exactly balance Abe and Barry (no child is winning the tug-o-war for the toy). We can label our forces A, B, and E (from each child's name). These three forces are in equilibrium. If Abe is pulling toward the North and Barry is pulling toward the East, we want to find the total force R due to Abe and Barry (the Resultant of their forces). Note: in THIS case the two forces and R form a right-triangle (with R as the hypotenuse) - as seen using graphical vector addition. As a convention let's have NORTH upward and EAST rightward on this page.

a. Sketch an ACCURATE free-body diagram (three arrows outward from a point showing LABELED forces A, B, and E - each arrow a reasonable length and correct direction):
b. Sketch a labeled diagram for graphical addition of A and B to get R:
c. Show the calculation of the magnitude of R from the magnitudes of A and B:
d. Give the magnitude of force E (in units of Newtons):
e. Describe the direction of force E in terms of the "cardinal" directions (north, east, south, and/or west):

Solution :

c). force applied by Abe

    force applied by Barry

    force applied by Eric

    Resultant force

 in the vector form can be written as :

 in the vector form can be written as :

The resultant,

        = 84.853 N

d). As the three forces are in equilibrium, therefore,

e). The direction of the force exerted by Eric is exactly opposite to the direction of the resultant force.

The direction of the resultant force is :

  = 45°  north east

The direction of the force E is  45° west or  45° south west.

. west

-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