The work done by the engine is converted into kinetic energy of the motorbike+rider system:

where
W=6400 J is the work
m=200 kg is the mass of the system
v is the speed acquired by the motorbike
Rearranging the equation and substituting the numbers in, we find
One well-known application of density is determining whether or not an object will float on water. If the object's density is less than the density of water, it will float; if its density is less than that of water, it will sink.In fact, submarines dive below the surface of the water by emptying their ballast tanks