When calculating gravity between 2 objects, where should the distance be measure from?

Something that flows easily, like water

50 km equals how many meters?

A heat engine does 30 j of work per cycle while exhausting 50 j of waste heat. what is the engine's thermal efficiency?

If the energy bar was his only fuel, how far could a 68 kg person walk at 5 km/h?

In which scenario is the least amount of work done on a crate? A force of 120 N moves it 25 m. A force of 115 N moves it 26 m. A force of 130 N moves it 22 m. A force of 125 N moves it 27 m.

Through which medium would EM waves travel the fastest? A. The Ocean B. The Atmosphere C. Rocks

Average mass of a toy car (small, hot wheels) ?

A cannon directed straight upward launches a ball with an initial speed v. The ball reaches a maximum height h in a time t. Then, the same cannon is used to launch a second ball straight upward at a speed 2v.

Does the sun fuse hydrogen into helium or vice versa?

Is it possible to put a distance versus time graph to be universal go mine