Answer:
3.5 cm
Explanation:
mass, m = 50 kg
diameter = 1 mm
radius, r = half of diameter = 0.5 mm = 0.5 x 10^-3 m
L = 11.2 m
Y = 2 x 10^11 Pa
Area of crossection of wire = π r² = 3.14 x 0.5 x 10^-3 x 0.5 x 10^-3
= 7.85 x 10^-7 m^2
Let the wire is stretch by ΔL.
The formula for Young's modulus is given by


ΔL = 0.035 m = 3.5 cm
Thus, the length of the wire stretch by 3.5 cm.
The work done is the product between the intensity of the force applied F, the amount of the displacement d of the book and the cosine of the angle

between the direction of the force and the direction of the displacement:

In our problem, the student is lifting the book, so he is applying a force directed upward, and the book is moving upward, so F and d are parallel and therefore the angle is zero, so

Therefore, the work done is
Answer:

Explanation:
The weekly water consumption of Kimonoski is:






The total energy required per week for hot water is:



Answer:

Explanation:
The computation of the weight of the paper in newtons is shown below:
On the paper, the induced charge is of the same magnitude as on the initial charges and in sign opposite.
Therefore the paper charge is

Now the distance from the charge is

Now, to raise the paper, the weight of the paper acting downwards needs to be managed by the electrostatic force of attraction between both the paper and the charge, i.e.




Four electrons are placed at the corner of a square
So we will first find the electrostatic potential at the center of the square
So here it is given as

here
r = distance of corner of the square from it center



now the net potential is given as


now potential energy of alpha particle at this position

Now at the mid point of one of the side
Electrostatic potential is given as

here we know that



now potential is given as


now final potential energy is given as

Now work done in this process is given as


