One level below the highest
It depends on the gearing of your vehicle. I would use the second gear in my car.
If you're referring to what gear to use when driving a manual transmission automobile that will vary depending on the vehicle. Me personally, based on my car, if I'm doing 30 mph I'm typically in 2nd gear. If it is a 4 speed you would normally be in 3rd. If it is a 5 speed you would be in 4th. A 6 speed you would be in 5th.
2nd or 3rd gears
Second gear should handle the 15 - 25 mph range nicely, but if the engine seems to be racing a little, third gear probably would be better. It depends upon whether there is an up- or down- slope in the road, and the weight of the car.
2nd gear. (the gear you would use from about 15-35mph)
Not sure when you say low speed. Not knowing what your driveline ratio is I will just use some basic numbers .If 20 MPH is your speed and you were in first gear your engine RPM's would be 3000, if you were in second gear at 20MPH your engine RPM's would be 2500 , if you were in third gear at 20MPH your engine RPM's would be 2000. A difference of 1000 RPM's from low to high gear. Lower engine RPM's less fuel used.
He lived in the zone where there was no water. Once I got into the right mental zone, I had no trouble studying. The school zone's speed limit was 10 m.p.h.
It would depend on the conditions you need to survive in. Cold weather gear would not be much use in the desert
It would depend on the conditions you need to survive in. Cold weather gear would not be much use in the desert
The gear ratio for top gear is chosen to produce maximum speed, which occurs at a speed where the engine's maximum power is take up with maintaining a constant speed (on the level). For cars the overall ratio for top gear is 3.5 to 4.5 : 1. For example, if the engine's maximum power is 100 bhp at 6300 rpm, and that power can drive the car at the maximum speed of 110 mph, the overall ratio is chosen to give 6300 rpm at 110 mph.
To convert mph to kmph, 1.61. For kmph to mph, 0.62
The lower the gear, the greater the torque multiplication. You will get maximum pulling power from reverse. I presume, however, that you merely wish to go forward rather than to haul someone out of a snow bank. If the snow is deep and the roads are expecially nasty, I recommend a lower gear. Be careful, however, not to over rev your engine. I would not recommend exceeding 20 mph in first. Second should be good up to 40 mph. Above that speed I recommend third, fourth or overdrive. Hope this helps.