Answer:
B. +m
Explanation:
The magnification of an image is defined as the ratio between the size of the image and of the object:

where we have
y' = size of the image
y = size of the object
There are two possible situations:
- When m is positive, y' has same sign as y: this means that the image image is upright
- When m is negative, y' has opposite sign to y: this means that the image is upside down
Therefore, the correct option representing an upright image is
B. +m
Answer:
force-strength,power or energy as an attribute of motion, movement or action. Example: Frictional force.
Answer:
a. 
b. 
Explanation:
I have attached an illustration of a solid disk with the respective forces applied, as stated in this question.
Forces applied to the solid disk include:

Other parameters given include:
Mass of solid disk, 
and radius of solid disk, 
a.) The formula for determining torque (
), is 
Hence the net torque produced by the two forces is given as a summation of both forces:

b.) The angular acceleration of the disk can be found thus:
using the formula for the Moment of Inertia of a solid disk;

where
= Mass of solid disk
and
= radius of solid disk
We then relate the torque and angular acceleration (
) with the formula:

Answer:
This is because the air outside is always cooler than the air inside, so after staying outside your body adapts to the cold air, when you come back inside, the cold air is still in you which makes the room seem warmer.