I motor =P motor u motor =240W48V=5A,

Because the motor does not necessarily run at rated power during operation,

Therefore, the working current of the motor is not necessarily 5A, so A is incorrect;

(2) The maximum electric energy that can be output when the battery is fully charged at one time:

W electricity =U electricity I electricity T electricity = 48V×12A× 3600s = 2.0736×106j, so B is incorrect;

(3) The electric energy that can be provided to the motor for each charge:

W Mechanical =W Electrical× 80% = 2.0736×106j× 80% =1.65888×106j,

Because the electric vehicle runs at a constant speed,

Therefore, the traction force F=f=40N,

Starting from W=Fs, the longest distance traveled:

S=W mechanical f =1.65888×106j40n = 41472m ≈ 4.1km, so c is correct;

(4) According to I=Qt, the maximum riding time of the electric bicycle is:

T = synchronous motor = 12Ah5A=2.4h,

Because the battery cannot be completely discharged when the electric vehicle is running,

Therefore, the maximum riding time of electric bicycle is less than 2.4h hours, so D is incorrect.

So choose C.