Answer:



Explanation:
From the question we are told that
Electric field of intensity 
Rectangle parameter Width
Length 
Angle to the normal 
Generally the equation for Electric flux at parallel to the yz plane
is mathematically given by



Generally the equation for Electric flux at parallel to xy plane
is mathematically given by



Generally the equation for Electric flux at angle 30 to x plane
is mathematically given by




I believe the answer would be 446.9 J.
When someone lifts a book from the ground, the work you use is positive. By lifting the book, you change it's energy and it's original place The book gains, kinectic energy.
Hope I helped.
Answer:
We know that for a pendulum of length L, the period (time for a complete swing) is defined as:
T = 2*pi*√(L/g)
where:
pi = 3.14
L = length of the pendulum
g = gravitational acceleration = 9.8 m/s^2
Now, we can think on the swing as a pendulum, where the child is the mass of the pendulum.
Then the period is independent of:
The mass of the child
The initial angle
Where the restriction of not swing to high is because this model works for small angles, and when the swing is to high the problem becomes more complex.