What does a horizontal line on a position time graph indicate

Astone is thrown into a pond. what happens to the amplitude of the resulting waves as they get farther from the point where the stone hit the water? explain.

Rank the automobiles based on the magnitude of the force needed to stop them, from largest to smallest.2000 kg car going 5m/s500 kg car going 20 m/s1000 kg car going20m/s500 kg car going10m/s1000 kg car going10/s4000 kg car going 5m/s 0 0 603

How can you increase the strength of an electromagnet?