Answer: option A. r = 3x+2y
Explanation:
Vector r is plotted on the graph. On x-axis each small division corresponds to 1 unit. Similarly on y-axis, each small division corresponds to one unit.
The vector is the resultant of addition of its x and y components. we would draw perpendicular to the x-axis and y-axis from the head of vector r.
On x-axis,
= +3 units
on y-axis,
= +2 units

Hence, vector r can be written as: r = 3x + 2y . Correct option is A.
a)
, 
The work done by the student in each trial is equal to the gravitational potential energy gained by the student:

where
m = 68 kg is the mass of the student
g = 9.8 m/s^2 is the acceleration of gravity
is the gain in height of the student
For the first student,
, so the work done is

The second student runs up to the same height (3.5 m), so the work done by the second student is the same:

2)
, 
The power exerted by each student is given by

where
W is the work done
t is the time taken
For the first student,
and
, so the power exerted is

For the second student,
and
, so the power exerted is

Answer:
The Electric flux will be 
Explanation:
Given
Strength of the Electric Field at a distance of 0.158 m from the point charge is

We know that the flux of the Electric Field can be calculated by using Gauss Law which is given by

Let consider a sphere of radius 0.158 m as Gaussian Surface at a distance of 0.158 m from the point charge and Let
be the flux of the Electric Field coming out\passing through it which is given by

It can be observed that same amount of flux which is passing through the Gaussian sphere of radius 0.158 is also passing through the Gaussian sphere of radius 0.142 m at a distance of 0.142 m from its centre.
Also it can be observed that the charge inside the two Gaussian Sphere mentioned have same value so the Flux of electric field through them will also be same.
So the electric flux through the surface of sphere that has given charge at its centre and that has radius 0.142 m is 
D) It isn't accelerating
This is because if both sides are pushing with the exact same force, than one force is not overpowering the other, therefor the wheelbarrow would not be moving.