Answer: 8Ω
Explanation:
Since there are two resistors of 4Ω
connected in series, the total resistance (Rtotal) of the circuit is the sum of each resistance.
i.e Rtotal = R1 + R2
R1 = 4Ω
R2 = 4Ω
Rtotal = ?
Rtotal = 4Ω + 4Ω
Rtotal = 8Ω
Thus, the total resistance of the circuit is 8Ω
I'm trying to make an electromagnet that's strength is constantly getting incremented by small amounts every second. I need to know, which would have a greater effect on the electromagnet's strength, amps or volts? (I know increasing the turns and/or density of the magnet wire will increase the strength, but I am looking for answers other than that particular one.)
Answer: (d)
Explanation:
Given
Mass of object 
Speed of object 
Mass of object at rest 
Suppose after collision, speed is v
conserving momentum

Initial kinetic energy

Final kinetic energy

So, it is clear there is decrease in kinetic energy . Thus, energy decreases and velocity becomes 2 m/s.
15.49 should be the answer if that is 12 watt battery.