Answer & Explanation:
In physics, a contact force is a force that acts at the point of contact between two objects, in contrast to body forces. Contact forces are described by Newton's laws of motion, as with all other forces in dynamics. Contact force is the force in which an object comes in contact with another object. Contact forces are also direct forces. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car up a hill or kicking a ball or pushing a desk across a room are some of the everyday examples where contact forces are at work. In the first case the force is continuously applied by the person on the car, while in the second case the force is delivered in a short impulse.
I would say the answer is emissions. These are the particles that are not supposed to be present in air but due to the production of different substances from humans daily activities these substances go with the air we breath. Hope this helped.
is the Lewis base in the following reaction:
→ 
<h3>What is lewis base? </h3>
Lewis base is a species that donates an electron pair.
In the above-given chemical equation, the is the lewis base which is donating an electron pair to the central atom of 
to form 
.
Hence, is the Lewis base in the following reaction:
→
Learn more about the lewis base here:
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The spaceship does not have any gravitational pull. A spaceship can not produce its own gravity like Earth does.
