Do you think oppositional or symbiotic relationships are more beneficial (important) to an ecosystem? GUYS HELPP!

We put a force of 50n on an object and the acceleration is 100 m/s². what is the mass of the object?

What object a collides with object b and bounces back its final momentum is?

Arigid tank is divided into two equal parts by a partition. one part of the tank contains 3 kg of compressed liquid water at 400 kpa and 60°c while the other part is evacuated. the partition is now removed, and the water expands to fill the entire tank. determine the entropy change of water during this process, if the final pressure in the tank is 40 kpa. use steam tables.