what is the relation between the mass & speed of an object in motion?

The greater the speed of an object the greater its potential energy. A faster object will do more damage upon an impact than a slower object of the same mass.

Absolutely none, my dear. Sorry. Nobody knows what their own speed is. Do you? There is one for driving down the road, one for turning with the earth, one for going round the sun, and one for spinning within the orbit in our galaxy, and there is one for our galaxy rushing through space at some fantabulous speed. Add all that up and we still wouldn't know what else we are moving round in. And while you and I sit side by side in that car, with the same universal speed, whatever that may be, I am fat and you are slim, and there is absolutely no relation between your mass and the speed. Nor mine and the speed.

Or perhaps if you increase your walking speed more each day, your mass may grow less from day to day. It's a good thought. That's the only relation between the mass and speed of an object in motion.

Oh, I forget, if the object is a snowball and you roll it down a hillslope in Aspen, then the greater the speed the greater the mass. Hmmm. There must be more answers than this. Can anyone else tell us?

According to Einsteins general theory of relativity, mass of an object increments proportionally to the speed it is moving at. An object moving at the speed of light would have an infinite mass!!

According to classical mechanic, mass times acceleration (rate of speed change) equal to force.

But in realitivity, mass increase exponentially to speed, when near the speed of light.

Depends on what mass you mean. The relativistic mass will increase with speed m = m0/sqrt(1-v2/c2), going towards infinity as the speed v approaches speed of light c

at speeds below about 0.3 times the speed of light, speed has no effect of mass, so the mass of, say, a plane or a car, will be pretty much unchanged irrespective of the speed.

around 0.3 times the speed of light, your mass will increase by about 5 percent

at 0.42x speed of light, mass will be 10 percent higher

0.55x speed of light, mass will be 20 percent higher

at 0.87x speed of light, mass will have doubled

at 99.5 percent of the speed of light, mass will be 10 times larger

at 99.995 percent of the speed of light, mass will be 100 times larger

at 99.99995 percent of the speed of light, mass will be 1000 times larger (than mass at rest)

and so on

e = m times the speed of light squared.