e..oo AT&T; 4:54 PM LonCAPA Homework Electric Car Part A A lightweight electric
ID: 1773676 • Letter: E
Question
e..oo AT&T; 4:54 PM LonCAPA Homework Electric Car Part A A lightweight electric car is powered by sixteen 12 V batteries. At a speed of 70 km/h, the average frictional force is 1050 N. What must be the power of the electric motor if the car is to travel at a speed of 70 km/h? 2.04x104 w You are correct Your receipt no. is 161-4988 rl Part B If each battery can deliver a total charge of 180 Ah before recharging, what is the total charge in coulombs that can be delivered by the sixteen batteries before recharging? 1.04x10' c You are correct. Previous Tries Your receipt no. is 161-859 Part C What is the total electric energy delivered by the sixteen batteries before recharging? 1.24x108j You are correct Your receipt no. is 161-3191 ) Part DExplanation / Answer
We can use P = fv to find the power the electric motor must develop to move the car at 70 km/h against a frictional force of 1050 N. We can find the total charge that can be delivered by the 16 batteries using Q = NIt . The total electrical energy delivered by the 16 batteries before recharging can be found using the definition of emf. We can find the distance the car can travel from the definition of work and the cost per kilometer of driving the car this distance by dividing the cost of the required energy by the distance the car has traveled.
v = 70 km/h = 19.4 m/s
a) P = f*v = 1050*19.4 = 2.04*10^4 W
b) Q = I*t = 180*3600*16 = 1.04*10^7 C
c) W = Q*V = 1.04*10^7*12 = 1.248*10^8 J
d) Relate the amount of work the batteries can do to the work required to overcome friction:
W = fd d = W/f = 1.248*10^8/1050 = 118857.1 m
e) The cost per kilometer is the ratio of the cost of the energy to the distance traveled before recharging:
Cost/km = (0.1010)*V*I*t/d = (0.1010*12*16*180)/118857.1 = $0.03/m
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