Which of the following is coldest layer of the earth's atmosphere? a. troposphere c. mesosphere b. stratosphere d. thermosphere

Consider a production line with five stations. station 1 can produce a unit in 9 minutes. station 2 can produce a unit in 10 minutes. station 3 has two identical machines, each of which can process a unit in 12 minutes (each unit only needs to be processed on one of the two machines. station 4 can produce a unit in 5 minutes. station 5 can produce a unit in 8 minutes. which station is the bottleneck station?

1,990,000,000,000,000,000,000,000,000,000 in scientific notation

Based on the diagram of the electric field lines around the two spherical charges, what are the signs of the left and right charge respectively?