Carole is very tired and makes coffee. Newton would say that she must use her hand to pick up the cup, because an object at rest will stay at rest unless acted upon by an external force. <em>(B)</em>
Complete Question
The diagram for this question is shown on the first uploaded image
Answer:
The magnitude is
, the direction is into the page
Explanation:
From the question we are told that
The current is 
The radius of arc bc is 
The radius of arc da is 
The length of segment cd and ab is = 
The objective of the solution is to obtain the magnetic field
Generally magnetic due to the current flowing in the arc is mathematically represented as
Here I is the current
is the permeability of free space with a value of 
r is the distance
Considering Arc da

Where
is the angle the arc da makes with the center from the diagram its value is 
Now substituting values into formula for magnetic field for da
![B_{da} = \frac{4\p *10^{-7} * 12}{4 \pi (0.20)}[\frac{2 \pi}{3} ]](https://tex.z-dn.net/?f=B_%7Bda%7D%20%3D%20%5Cfrac%7B4%5Cp%20%2A10%5E%7B-7%7D%20%2A%2012%7D%7B4%20%5Cpi%20%280.20%29%7D%5B%5Cfrac%7B2%20%5Cpi%7D%7B3%7D%20%5D)
![= \frac{10^{-7} * 12}{0.20} * [\frac{2 \pi}{3} ]](https://tex.z-dn.net/?f=%3D%20%5Cfrac%7B10%5E%7B-7%7D%20%2A%2012%7D%7B0.20%7D%20%2A%20%5B%5Cfrac%7B2%20%5Cpi%7D%7B3%7D%20%5D)

Looking at the diagram to obtain the direction of the current and using right hand rule then we would obtain the the direction of magnetic field due to da is into the pages of the paper
Considering Arc bc

Substituting value
![B_{bc} = \frac{4 \pi *10^{-7} * 12}{4 \pi (0.30)} [\frac{2 \pi}{3} ]](https://tex.z-dn.net/?f=B_%7Bbc%7D%20%3D%20%5Cfrac%7B4%20%5Cpi%20%2A10%5E%7B-7%7D%20%2A%2012%7D%7B4%20%5Cpi%20%280.30%29%7D%20%5B%5Cfrac%7B2%20%5Cpi%7D%7B3%7D%20%5D)

Looking at the diagram to obtain the direction of the current and using right hand rule then we would obtain the the direction of magnetic field due to bc is out of the pages of the paper
Since the line joining P to segment bc and da makes angle = 0°
Then the net magnetic field would be



Since
then the direction of the net charge would be into the page
(C) Air Resistance
<u>Explanation:</u>
When an object falls through air, air resistance acts on it in upward direction. When air resistance acts, acceleration during a fall will be less than g because air resistance affects the motion of the falling objects by slowing it down. Air resistance depends on two important factors - the speed of the object and its surface area. Increasing the surface area of an object decreases its speed.