I thought you were going to ask for the resistance of the unknown
series resistor. Since you only want the equivalent resistance of the
circuit, you don't even need to know the resistance of the lamp.
I = E / R
Current through the circuit = (voltage of the battery) / (circuit resistance).
0.5 = (12) / R
Multiply each side by 'R' : (0.5) R = 12
Multiply each side by 2 : <em>R = 24 ohms</em>
(Since the resistance of the lamp is 10 ohms, the
unknown series resistor is the other 14 ohms.)
Assume a 2D plane and both the birds start at origin. +X is east, -X is west, +Y is North, -Y is South.
So, after travel position of bird1 is (-2.8, 2.7) and bird2 is (-2.7,2.8);
slope of bird1 is 2.8/2.7
slope of bird2 is 2.7/2/8
Now we have two solpes b1 and b2
formula = (b2-b1)/(1+b1*b2);
Answer:

Explanation:
If the collision is elastic and exactly head-on, then we can use the law of momentum conservation for the motion of the 2 balls
Before the collision

After the collision

So using the law of momentum conservation


We can solve for the speed of ball 1 post collision in terms of others:

Their kinetic energy is also conserved before and after collision


From here we can plug in 






C is correct because they would repel each other A is wrong be they wouldn't repel And B is wrong because they shouldn't be repelling each other