A. Discovering a quick way to handle a new problem
Answer:
From question (a) and (b) the pendulum motion is perpendicular to the force so the normal force will do no work and the tension in the string of the pendulum will not work

And
so

c
An example will be a where a stone is attached to the end of a string and is made to move in a circular motion while keeping the other end of the string in a fixed position
d
A dog walking along a surface which has friction, here the frictional force would acting in the direction of the motion and this would do positive work
Explanation:
It looks blue as it is only reflecting blue light
Answer:
The electric field will be zero at x = ± ∞.
Explanation:
Suppose, A -2.0 nC charge and a +2.0 nC charge are located on the x-axis at x = -1.0 cm and x = +1.0 cm respectively.
We know that,
The electric field is

The electric field vector due to charge one

The electric field vector due to charge second

We need to calculate the electric field
Using formula of net electric field


Put the value into the formula




Put the value into the formula


If x = ∞, then the equation is be satisfied.
Hence, The electric field will be zero at x = ± ∞.
Answer:
Part a)

Part b)

Part c)

Part d)

Explanation:
Part a)
While bucket is falling downwards we have force equation of the bucket given as

for uniform cylinder we will have

so we have


now we have




now we have


Part b)
speed of the bucket can be found using kinematics
so we have



Part c)
now in order to find the time of fall we can use another equation



Part d)
as we know that cylinder is at rest and not moving downwards
so here we can use force balance


