Explanation:
Formula for angle subtended at the center of the circular arc is as follows.

where, S = length of the rod
r = radius
Putting the given values into the above formula as follows.

= 
= 
= 
Now, we will calculate the charge density as follows.

= 
= 
Now, at the center of arc we will calculate the electric field as follows.
E = 
= 
= 34.08 N/C
Thus, we can conclude that the magnitude of the electric eld at the center of curvature of the arc is 34.08 N/C.
A waves frequency (in Hertz) is how many crests pass by a point per second. easily confused with period, which is the amount of time it takes for a full wave to pass by a certain point
Speed = wavelength × frequency
giving that frequency is 0, wavelength and speed are directionally proportional. wavelength decrease = speed decrease
The force acting on his feet.