Answer:
If the system consists of the block only, the work done by the gravity is negative.
If the system consists of the block and the earth the work done by the gravity is zero.
Explanation:
If the system consists of the block only, then the system experiences two external forces: one exerted by the hand that lifts the block vertically upward and other exerted by the earth (gravity), which is opposed to the movement of the system, so the work done by gravity is negative.
On the other hand, if the system consists of the block and the earth, then only exists a external force which is the exerted by the hand. So, the force exerted by gravity is zero.
The annual production of carbon dioxide is 124121.49×10^{6}[/tex] kg.
First we calculate the fuel consumed by each car in a year
Fuel consumed=6990/21.4=326.63 gallon
Now we calculate the amount of fuel consumed by 40 million cars in a year
Fuel consumed=326.63*40*10^6=13065.42 million gallon,
Now we can calculate the annual production of carbon dioxide in the USA
CO2 production rate=9.50*13065.42=124121.49*10^6 kg
Therefore the annual production of carbon dioxide in USA is 124121.49×10^{6}[/tex] kg
Answer:
c
Explanation:
it's the only one that makes sense
