Answer:
D.) 1m/s
Explanation:
Assume the initial angle of the swing is 12.8 degree with respect to the vertical. We can calculate the vertical distance from this initial point to the lowest point by first calculate the vertical distance from this point the the pivot point:

where L is the pendulum length
The vertical distance from the lowest point to the pivot point
is the pendulum length 2m
this means the vertical distance from this initial point to the lowest point is simply:

As the pendulum travel (vertically) from the initial point to the bottom point, its potential energy is converted to kinetic energy:


where m is the mass of the pendulum, g = 10 m/s2 is the constant gravitational acceleration, h = 0.05 is the vertical it travels, v is the pendulum velocity at the bottom, which we are trying to solve for.
The m on both sides of the equation cancel out


so D is the correct answer
The best logical answer is A
Answer:

and

Explanation:
Given:
- first charge,

- second charge,

- position of first charge,

- position of second charge,

Now since there are only 2 charges and of the same sign so they repel each other. This repulsion will be zero at some point on the line joining the charges.
<u>Now, according to the condition, electric field will be zero where the effects of field due to both the charges is equal.</u>

- since first charge is greater than the second charge so we may get a point to the right of the second charge and the distance between the two charges is 1 meter.





Since we have assumed that the we may get a point to the right of second charge so we calculate with respect to the origin.

and

D is the best answer. In many physics problems we treat an extended object as if it were a point with the same mass located at the center of mass.
Refractive Index is a ratio of two similar physical quantity which is dimension less
refractive index = sin I / sin r
therefore it doesn't have a unit.