He would die.
The mass of an object weighing 63 N on Earth would be 6.43 kg. This is calculated by dividing the weight (in Newtons) by the acceleration due to gravity (9.81 m/s^2).
Mach is the speed of an object expressed as a multiple of the speed of sound in the same medium. Thus, an object travelling at 686 metres per second through air, at sea level, is travelling at Mach 2 because sound would travel through it at 343 m/s. However, it the object was travelling under water at the same speed then it would be travelling at approx Mach 0.46 since sound travels at 1484 m/s through water.
A kilogram is equals to 2.20462 pounds. An object weighing 55.8kg would weigh 123lbs.
nothing would happen
it would become longer
You compare its mass with something of known mass. In everyday earthbound conditions, this would mean weighing it on a set of weighing scales or on a spring balance.
it is impossible to fire a bullet a the speed of light
It could, if it contained enough air. To float on water, you would need about 1 liter of air for every kilogram you want to keep afloat.
No. For you to know the distance you need to know the time the object has been travelling and a function describing the speed of the object for the time it has been travelling. A direction is not required. correct but you missed direction can affect speed as climbing altitude would get slowed by gravity
The object would behave as a part of fluid and it will remain where it is kept.
The object would float in a given liquid.
The object would crash into the planet.