A2.0-n force acts horizontally on a 10-n block that is initially at rest on a horizontal surface. the coefficient of static friction between the block and the surface is 0.50. suppose that the block now moves across the surface with constant speed under the action of a horizontal 3.0-n force. which one of the following statements concerning this situation is false? the net force on the block is zero newtons. the coefficient of kinetic friction between the block and the surface is 0.30. the frictional force on the block has magnitude 3.0 n. the direction of the total force that the surface exerts on the block is vertically upward. the block is not accelerated.

None of the statement is false - all of them are true

Explanation:

Let's analyze each statement:

- The net force on the block is zero newtons. --> TRUE. In fact, the block is moving across the surface at constant speed: constant speed means zero acceleration, and according to Newton's second law,

F = ma

this also means a net force of zero newtons.

- The frictional force on the block has magnitude 3.0 N. --> TRUE. The horizontal acceleration of the block is zero, so the resultant of the horizontal forces must be zero:

where F = 3.0 N is the horizontal push and is the frictional force. From the equation, we find

- The coefficient of kinetic friction between the block and the surface is 0.30. --> TRUE. The frictional force is 3.0 N, and its expression is

where is the coefficient of kinetic friction and (mg)=10 N is the weight of the block. Solving for , we find

- The direction of the total force that the surface exerts on the block is vertically upward. --> TRUE. Since gravity is acting downward, and the block is not accelerating on the vertical direction neither, there must be an equal and opposite force acting upward on the block: and this force is the force exerted by the surface on the block.

- The block is not accelerated. --> TRUE: the block is moving at constant speed, so its acceleration is zero.

-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