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joja [24]
3 years ago
7

Which rule(s) is used for combining velocities?

Physics
1 answer:
DIA [1.3K]3 years ago
4 0

Answer: B. Vector rules

Explanation:

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Why society might initially reject a new scientific theory?
Irina18 [472]

I was about to say:  because people generally get comfortable with
what they think they know, and don't like the discomfort of being told
that they have to change something they're comfortable with.

But then I thought about it a little bit more, and I have a different answer.

"Society" might initially reject a new scientific theory, because 'society'
is totally unequipped to render judgement of any kind regarding any
development in Science. 

First of all, 'Society' is a thing that's made of a bunch of people, so it's
inherently unequipped to deal with scientific news.  Anything that 'Society'
decides has a lot of the mob psychology in it, and a public opinion poll or
a popularity contest are terrible ways to evaluate a scientific discovery.

Second, let's face it.  The main ingredient that comprises 'Society' ... people ...
are generally uneducated, unknowledgeable, unqualified, and clueless in the
substance, the history, and the methods of scientific inquiry and reporting.

There may be very good reasons that some particular a new scientific theory
should be rejected, or at least seriously questioned.  But believe me, 'Society'
doesn't have them.

That's pretty much why.
 
6 0
3 years ago
A box with a mass of 18 kg is pushed across the floor. It has coefficient of friction of 0.39. Calculate the force of friction i
Taya2010 [7]

Answer:

68.8 N

Explanation:

From the question given above, the following data were obtained:

Mass (m) of box = 18 Kg

Coefficient of friction (μ) = 0.39

Force of friction (F) =?

Next, we shall determine the normal force of the box. This is illustrated below:

Mass (m) of object = 18 Kg

Acceleration due to gravity (g) = 9.8 m/s²

Normal force (N) =?

N = mg

N = 18 × 9.8

N = 176.4 N

Finally, we shall determine the force of friction experienced by the object. This is illustrated below:

Coefficient of friction (μ) = 0.39

Normal force (N) = 176.4 N

Force of friction (F) =?

F = μN

F = 0.39 × 176.4

F = 68.796 ≈ 68.8 N

Thus, the box experience a frictional force of 68.8 N.

3 0
2 years ago
:) What is practical machine? what is the reda<br>tion between MA and VR in a practical<br>machine?​
denis-greek [22]
Answer: For ideal machine efficiency = 1. Hence M.A = V. R. The V. R of an ideal machine and the practical machine is a constant or is the same for both
3 0
3 years ago
] A new coal-fired 750 MWe power plant with a thermal efficiency of 42% burns 9000 Btu/lb coal, which contains 1.1% sulfur. a. I
Valentin [98]

Answer:

The net emissions rate of sulfur is 1861 lb/hr

Explanation:

Given that:

The power or the power plant = 750 MWe

Since the power plant with a thermal efficiency of 42% (i.e. 0.42) burns 9000 Btu/lb coal, Then the energy released per one lb of the coal can be computed as:

\mathtt{=( 0.42\times 9000\times 1055.06) J}

= 3988126.8  J

= 3.99 MJ

Also, The mass of the burned coal per sec can be calculated by dividing the molecular weight of the power plant by the energy released per one lb.

i.e.

The mass of the coal that is burned per sec =\dfrac{750}{3.99}

The mass of the coal that is burned per sec = 187.97 lb/s

The mass of sulfur burned  = \dfrac{1.1}{100} \times 187.97 \  lb/s

= 2.067 lb/s

To hour; we have:

= 7444 lb/hr

However, If a scrubber with 75% removal efficiency is utilized,

Then; the net emissions rate of sulfur is (1 - 0.75) × 7444 lb/hr

= 0.25 × 7444 lb/hr

= 1861 lb/hr

Hence, the net emissions rate of sulfur is 1861 lb/hr

8 0
2 years ago
A traffic light of weight 100 N is supported by two ropes that make 30-degree angle with the horizontal. What is the vertical co
alina1380 [7]

Answer:

T_{vertical} = 50 N

Explanation:

given,

traffic light weight = 100 N

angle at which the rope is supported = 30°

vertical component of force = ?

2 T sin \theta= W

2 T sin 30^0= 100

T = \dfrac{100}{2 sin 30^0}

T = 100\ N

T_{vertical} = T sin 30^0

T_{vertical} = 100\times \dfrac{1}{2}

T_{vertical} = 50 N

5 0
3 years ago
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