1) 30 volts is correct
2) Rt = (4x6)/(4+6)=2.4 Ω
3) P = I^2 x R = 36 W
we use AC because it's easy to transmit via 3 phase on cables and easy to step up and down
The focal point of a concave mirror is halfway along the radius, therefore the radius would be 2•16= 32 cm
Answer:
Distance, d = 61.13 ft
Explanation:
It is given that,
Initial speed of the car, u = 50 mi/h = 73.34 ft/s
Finally, it stops i.e. v = 0
Deceleration of the car, 
We need to find the distance covered before the car comes to a stop. Let the distance is s. It can be calculated using third law of motion as :



s = 61.13 ft
So, the distance covered by the car before it comes to rest is 61.13 ft. Hence, this is the required solution.