I'm having a difficult time answering this question. I think I'm just converting the units wrong somewhere:
You're the CEO of a courier company, and you decide to select an electric car for your fleet of vehicles. A particular car has a mass of 1600kg and is powered by 26 12−V batteries connected in series, for a total of 312 V. Batteries are rated at 100 ampere-hours, which means they can deliver 100 A for 1 h, 1 A for 100 h, or any combination that equals 100A⋅h. When the batteries are connected in series, the charge output of all the batteries is the same as one battery-in this case 100A⋅h. The motor is 85% efficient in converting electrical energy to mechanical energy in the drive wheels. A test report says the car can climb a 12∘ slope at a speed of 50km/h. How long can the car maintain that speed at this angle?
I'm using mgsin12 to calculate the force of gravity acting on the car and 100*.85*312 to calculate the power delivered by the battery. My confusion lies in how I should incorporate 50km/h to solve the problem.