The alternator in a car consists of a rectangular coil, with 250 turns of wire and area 0.01 m^2, rotating in a 0.1 t magnetic field. (the field is produced by a direct-current electromagnet.) if the rotation rate is 10^3 rpm, what is the peak output voltage?

26.17  V

Explanation:

In a alternator , an ac voltage is produced whose magnitude of voltage varies sinusoidally.

Maximum voltage induced = nBAω

where n is no of turns , B is magnetic field , A is area of the coil and ω is angular velocity .

Rate of rotation   n  = 1000rpm = 1000/60 rps = 16.67 rps

angular velocity ω = 2π n = 2π x 16.67 = 104.68 rad / s

Putting all values in the given equation above

Max voltage = 250 x .1 x .01 x 104.68

= 26.17  V

i think it would be 80 km/h because 30 + 50 = 80 (sorry if this not the right answer i'm trying my best)