a tennis ball bounces off a wall and its momentum is reversed. Explain this using the conservation of momentum and the word closed and isolated

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?

Aproduction line at v. j. sugumaran's machine shop has three stations. the first station can process a unit in 7 minutes. the second station has two identical machines, each of which can process a unit in 16 minutes (each unit only needs to be processed on one of the two machines). the third station can process a unit in 10 minutes. ▼ is the bottleneck station, with a bottleneck time of nothing minutes per unit (enter your response as a whole number).