Answer:
A) and B) are correct.
Explanation:
If the object is at rest, it means that no net force is exerted on it.
As the object experiences a downward gravitational force from Earth, in order to be at rest, it must experience an upward force with the same magnitude as the gravitational force on the object.
This force is supplied by the normal force, which can adopt any value in order to meet the condition imposed by Newton´s 2nd Law, and is always perpendicular to the surface on which the object is placed (in this case, the ground).
At a molecular level, this normal force is supplied by the bonded molecules of the ground that behave like small springs being compressed by the molecules of the object, exerting an upward restoring force upward on them.
So, the statements A) and B) are true.
Answer:

Explanation:
From the question we are told that
Distance 
Time
Time
Generally the the equation for the distance traveled is mathematically given as



Generally equation for speed of side walk is mathematically given as




Answer:
D. A negative externality.
Explanation:
Particulate pollution is a form of pollution that is responsible for the degradation of the environment.
Particulate matter is also referred to as particle pollution or atmospheric aerosol particles and it can be defined as a complex microscopic mixture of liquid droplets and solid particles that are suspended in air.
An externality is typically an unwarranted cost or benefit by a manufacturer or producer of goods and services that affects a third party.
In Economics, an externality could either be positive or negative depending on its effect on a third party.
A negative externality arises when the production or consumption of a finished product or service has negative impact (cost) on a third party.
In conclusion, air pollution is an example of a negative externality because it causes harm to a third party.
Answer:
velocity
Explanation:
I think i dont really know