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rusak2 [61]
3 years ago
10

2. Human Impact on the Environment

Physics
1 answer:
Kitty [74]3 years ago
8 0
Burning fossil fuels emits a number of air pollutants that are harmful to both the environment and public health. Sulfur dioxide (SO2) emissions, primarily the result of burning coal, contribute to acid rain and the formation of harmful particulate matter.
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How do crystalline solids differ from amorphous solids?
LUCKY_DIMON [66]
Crystalline crystals have sharp, well-defined melting points. Amorphous Solids don't have melting points.
6 0
3 years ago
Gasoline burns inside a car’s engine. how does this fuel enable a car to move?
Svetllana [295]
<span> The purpose of a gasoline car engine is to convert gasoline into motion so that your car can move. Currently the easiest way to create motion from gasoline is to burn the gasoline inside an engine.
Therefore, a car engine is an internal combustion engine -- combustion takes place internally.
There is such a thing as an external combustion engine. A steam engine in old-fashioned trains and steam boats is the best example of an external combustion engine. The fuel (coal, wood, oil, whatever) in a steam engine burns outside the engine to create steam, and the steam creates motion inside the engine. Internal combustion is a lot more efficient (takes less fuel per mile) than external combustion, plus an internal combustion engine is a lot smaller than an equivalent external combustion engine. This explains why we don't see any cars using steam engines.

To understand the basic idea behind how a reciprocating internal combustion engine works, it is helpful to have a good mental image of how "internal combustion" works.

One good example is an old Revolutionary War cannon. You have probably seen these in movies, where the soldiers load the cannon with gun powder and a cannon ball and light it. That is internal combustion, but it is hard to imagine that having anything to do with engines.

A potato cannon uses the basic principle behind any reciprocating internal combustion engine: If you put a tiny amount of high-energy fuel (like gasoline) in a small, enclosed space and ignite it, an incredible amount of energy is released in the form of expanding gas. You can use that energy to propel a potato 500 feet. In this case, the energy is translated into potato motion. You can also use it for more interesting purposes. For example, if you can create a cycle that allows you to set off explosions like this hundreds of times per minute, and if you can harness that energy in a useful way, what you have is the core of a car engine! </span>
8 0
3 years ago
You are an engineer in charge of designing a new generation of elevators for a prospective upgrade to the Empire State Building.
DanielleElmas [232]

Answer:

   t_total = 23.757 s

Explanation:

This is a kinematics exercise.

Let's start by calculating the distance and has to reach the limit speed of

v = 18.8 m / s

         v = v₀ + a t₁

the elevator starts with zero speed

         v = a t₁

         t₁ = v / a

         t₁ = 18.8 / 2.40

         t₁ = 7.833 s

in this time he runs

         y₁ = v₀ t₁ + ½ a t₁²

         y₁ = ½ a t₁²

         y₁ = ½ 2.40 7.833²

         y₁ = 73.627 m

This is the time and distance traveled until reaching the maximum speed, which will be constant throughout the rest of the trip.

           x_total = x₁ + x₂

           x₂ = x_total - x₁

           x₂ = 373 - 73,627

           x₂ = 299.373 m

this distance travels at constant speed,

           v = x₂ / t₂

           t₂ = x₂ / v

           t₂ = 299.373 / 18.8

           t₂ = 15.92 s

therefore the total travel time is

           t_total = t₁ + t₂

           t_total = 7.833 + 15.92

           t_total = 23.757 s

6 0
3 years ago
1. Define friction. Name and describe two kinds of friction.
jeka57 [31]

Answer:

Friction is a force that holds back the movement of a sliding object.

Explanation:

The two types of friction: Static friction and Kinetic friction.  Static friction operates between two surfaces that aren't moving relative to each other, while kinetic friction acts between objects in motion.

6 0
3 years ago
A machine has a mechanical advantage of 4.5. What force is put out by the machine if the force applied to the machine is 800 N?
Ghella [55]

If the machine's mechanical advantage is 4.5, that means that

Output force = (4.5) x (Input force) .

We know the input force, and we need to find the output force.  Rather than wander around the room looking at the floor while our hair smolders, let's try putting the numbers we know into the equation I wrote up there.  OK ?

Output force = (4.5) x (Input force)

Output force = (4.5) x (800 N)

Now dooda multiplication:

<em>Output force = 3,600 N</em> .  

That's exactly what the question asked for.  So we're done !

3 0
3 years ago
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