The starter motor of a car engine draws a current of 180 A from the battery. The copper wire to the motor is?

(a) current is amount of charge/time => amt of charge = current x time=180A x 0.70 sec

(b) You need to find the drift velocity of electrons for this part. The current I = nev_dA, => v_d = I/neA

or v_d = 180A/(pir^2 ne ). The distance travelled by electrons in 0.70 sec = v_d x (0.7 sec)

find n and e from your book or Google and plug it in and calculate.

Current is defined as the rate at which charges pass.

I = Q/t

It = Q

180 A * 0.7 s = 126 As = 126 C

v = I M / (ρ Na q f A)

v = (180 A) (63.546 g/mol) / [ (8.96 g/mL) * (6.02214*10²³ atoms / mol) * (1.6022*10⁻¹⁹ C/electron) * (1 electron/atom) * ( π (2.5 mm)² ) ]

I is the current, M is the molar mass of copper

ρ is the density of copper, Na is Avogadro's number

q is the coulomb charge on the electron (the fundamental charge)

f is the number of free electrons per atom that copper has. A is the cross-sectional area of the wire.

Make sure units match. Follow the dimensional analysis.