The question is incomplete. The complete question is :
A platypus foraging for prey can detect an electric field as small as 0.002 N/C.
-To give an idea of sensitivity of the platypus's electric sense, how far from a +80nC point charge does the field have this magnitude?
Solution :
Given electric field, E = 0.002 N/C
Charge, Q = + 80 nC
or 
R = 600 m
This is the distance of the charge from the point of observations.
Answer:
117.6°
Explanation:
The vertical component of a force directed at some angle α from the vertical is ...
F·cos(α)
We want the vertical components of the wolf's force (Fw) and Red's force (Fr) to total zero. So for some angle from vertical α, Red's force will satisfy ...
Fw·cos(25°) + Fr·cos(α) = 0
cos(α) = -Fw/Fr·cos(25°) ≈ -(6.4 N)/(12.5 N)·0.906308 ≈ -0.464030
α ≈ arccos(-0.464030) ≈ 117.6°
Red was pulling at an angle of about 117.6° from the vertical.
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<em>Additional comment</em>
That's about 27.6° below the horizontal.
Answer:
It's the duration between successive new moons. Also called a lunation or synodic month, it has a mean period of 29.53059 days (29 days 12 hours and 44 minutes).
Using the given equation:
di = 20.0 * 10.0 / 20.0 - 10.0
di = 200/10
di = 20.0 cm
The answer is A.
