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Simora [160]
3 years ago
14

Xavier is roller skating at 14 km/h and tosses a set of keys forward on the ground at 8 km/h. The speed of the keys relative to

the ground is
Physics
1 answer:
Arturiano [62]3 years ago
4 0

Answer:

22 km/h

Explanation:

Given that,

Speed of Xavier, v = 14 km/h

He tosses a set of keys forward on the ground at 8 km/h, v' = 8 km/h

We need to find the speed of the keys relative to the ground. Let it is V.

As both Xavier and the keys are moving in same diretion. The relative speed wrt ground is given by :

V = v+v'

V= 14 + 8

V = 22 km/h

So, the speed of the keys relative to the ground is 22 km/h.

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A cube of water 10 cm on a side is placed in a microwave beam having Ea = 11 kV/m‘ The microwaves illuminate one faceofthe cube,
Shtirlitz [24]

Answer:

The time is 133.5 sec.

Explanation:

Given that,

One side of cube = 10 cm

Intensity of electric field = 11 kV/m

Suppose How long will it take to raise the water temperature by 41°C Assume that the water has no heat loss during this time.

We need to calculate the rate of energy transfer from the beam to the cube

Using formula of rate of energy

P=(0.80)IA

P=0.80\times\dfrac{c\mu_{0}E^2}{2}\times A

Put the value into the formula

P=0.80\times\dfrac{3\times10^{8}\times8.85\times10^{-12}\times(1.1\times10^{4})^2}{2}\times(10\times10^{-2})^2

P=1285.02\ W

We need to calculate the amount of heat

Using formula of heat

E =mc\Delta T

E =\rho Vc\Delta T

Put the value into the formula

E=1000\times(0.10)^3\times4186\times41

E=171626\ J

We need to calculate the time

Using formula of time

t=\dfrac{E}{P}

Put the value into the formula

t=\dfrac{171626}{1285.02}

t=133.5\ sec

Hence, The time is 133.5 sec.

3 0
4 years ago
Light from a laser of wavelength λ1 shines normally on a pair of narrow slits separated by distance D. This results in a differe
lana66690 [7]

Answer:

Explanation:

The angular position of first intensity maxima is given by the expression

= λ / d where λ is wave length of light and d is slit separation

putting the values given in the problem. ,

.02 = λ₁ / D

Now wavelength has been increased to 2λ₁

angular separation of first maxima

=  2λ₁ /D

= 2 x .02

= .04 radians.

6 0
3 years ago
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
When water is boiled under a pressure of 2.00atm, the heat of vaporization is 2.20×106J/kg and the boiling point is 120∘C. At th
Vikki [24]

Answer:

2033219.05 J

Explanation:

V = Volume

P = Pressure = 2 atm

m = Mass of water = 1 kg

L_v = Heat of vaporization = 2.2\times 10^6\ J/kg

Work done in an isobaric system is given by

W=-P\Delta V\\\Rightarrow W=-2\times 101325\times (1\times 10^{-3}-0.824)\\\Rightarrow W=166780.95\ J

Work done is 166780.95 J

Change in internal energy is given by

\Delta U=Q-W

Heat is given by

Q=mL_v\\\Rightarrow Q=1\times 2.2\times 10^6\\\Rightarrow Q=2.2\times 10^6\ J

\Delta U=2.2\times 10^6-166780.95\\\Rightarrow \Delta U=2033219.05\ J

The increase in internal energy of the water is 2033219.05 J

6 0
3 years ago
A 1200 kg elevator accelerated upwards at 2 m/s2. Draw a force diagram for the elevator. Calculate the force of tension in the c
pishuonlain [190]

Answer:

4800

Explanation:

You have to multiply the 1200 kg and the 2 m/s2. Then multiply the other 2 by the 2400 because it was the answer to the first part now after you multiply your answer is 4800.

6 0
4 years ago
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