If im correct 60,000 years ago
Answer:
I think it might be the third one... but I'm not sure.
Explanation:
I think k represents gravity because it's the string keeping the ball attached to the pole.
Answer:
Navigable rivers and geographical conditions.
Explanation:
Rivers and moderate distances between the countries have been an advantage for Europe because it makes it easy to transport goods all across the realm. Rivers and canals provided transportation routes for goods and people. Rivers use to transport goods between coastal harbors and the inland, aiding economic growth, and they bring people and goods together.
Answer: Water pollution can have disastrous effects on the environment.
Explanation:
- Pollution in the water can reach a point where there isn't enough oxygen in the water for the fish to breathe. The fish can suffocate and not have enough air.
- Pollution affects the entire food chain. Small fishes absorb pollutants, such as chemicals, into their bodies. Bigger fishes eat the smaller fishes and get the pollutants as well. Birds or other animals may eat the bigger fishes and be harmed by the pollutants. One example of this was the use of the insecticide (bug killer) DDT, which is when birds of prey ate fishes that were infected with it, they would lay eggs with thin shells. The population of birds of prey began to drop until DDT was banished.
- Sewage causes major problems in rivers. Bacteria in the water will use oxygen to break down the sewage. If there is too much sewage, the bacteria could use up oxygen until there won't be enough left for the fish.
- Water pollution from major events like acid rain or oil spills can completely destroy marine habitats.
- One of the most important commodities for life on planet Earth is clean water. For over 1 billion people on the planet, clean water is nearly impossible to get. Dirty, polluted water can make them sick enough to die.
