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vovikov84 [41]
3 years ago
8

How much heat is required to heat 2 kg of water from 25°C to 40°C?

Physics
1 answer:
Dominik [7]3 years ago
5 0

Answer:

126000 J

Explanation:

Applying,

Q = cm(t₂-t₁).................. Equation 1

Where Q = Amount of heat, c = specifc heat capacity of water, m = mass of water, t₁ = Initial temperature, t₂ = Final temperature.

From the question,

Given: m = 2 kg, t₁ = 25°C, t₂ = 40°C

Constant: c = 4200 J/kg.°C

Substitute these value into equation 1

Q = 2×4200(40-25)

Q = 2×4200×15

Q = 126000 J

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Suppose astronomers discover a radio message from a civilization whose planet orbits a star 35 light-years away. Their message e
Grace [21]

Answer:

The duration  is  T  =72 \  years /tex]Explanation:From the question we are told that     The  distance is  [tex]D  =  35 \ light-years = 35 *  9.46 *10^{15} = 3.311 *10^{17} \  m

  Generally the time it would take for the message to get the the other civilization is mathematically represented as

         t =  \frac{D}{c}

Here c  is the speed of light with the value  c =  3.08 *10^{8} \  m/s

=>     t =  \frac{3.311 *10^{17} }{3.08 *10^{8}}

=>     t =  1.075 *10^9 \ s

converting to years

           t =  1.075 *10^9 *  3.17 *10^{-8}

              t =  1.075 *10^9 *  3.17 *10^{-8}

            t =  34 \ years

Now the total time taken is mathematically represented as

      T  =  2*  t  +  2 + 2

=>   T  =  2* 34  +  2 + 2

=>   [tex]T  =72 \  years /tex]

4 0
3 years ago
One end of a 34-m unstretchable rope is tied to a tree; the other end is tied to a car stuck in the mud. The motorist pulls side
anyanavicka [17]

Answer:

Fc = 89.67N

Explanation:

Since the rope is unstretchable, the total length will always be 34m.

From the attached diagram, you can see that we can calculate the new separation distance from the tree and the stucked car H as follows:

L1+L2=34m

L1^2=L2^2=L^2=2^2+(H/2)^2  Replacing this value in the previous equation:

\sqrt{2^2+H^2/4}+ \sqrt{2^2+H^2/4}=34  Solving for H:

H=\sqrt{52}

We can now, calculate the angle between L1 and the 2m segment:

\alpha = atan(\frac{H/2}{2})=60.98°

If we make a sum of forces in the midpoint of the rope we get:

-2*T*cos(\alpha ) + F = 0  where T is the tension on the rope and F is the exerted force of 87N.

Solving for T, we get the tension on the rope which is equal to the force exerted on the car:

T=Fc=\frac{F}{2*cos(\alpha) } = 89.67N

7 0
3 years ago
Does the theory of relativity show that Newtonian mechanics is wrong?
valina [46]

Answer:

Einstein extended the rules of Newton for high speeds. For applications of mechanics at low speeds, Newtonian ideas are almost equal to reality. That is the reason we use Newtonian mechanics in practice at low speeds.

Explanation:

<em>But on a conceptual level, Einstein did prove Newtonian ideas quite wrong in some cases, e.g. the relativity of simultaneity. But again, in calculations, Newtonian ideas give pretty close to correct answer in low-speed regimes. So, the numerical validity of Newtonian laws in those regimes is something that no one can ever prove completely wrong - because they have been proven correct experimentally to a good approximation.</em>

4 0
3 years ago
Describe the full water cycle
sergey [27]

The water cycle (hydro-logic cycle), explains the constant motion of water on, above and below the surface of the Earth. The mass of water on Earth stays equally constant over time, although the severe portion of the water goes into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different forms: liquid, solid (ice) and vapor.

5 0
3 years ago
A river flows due south at 5 mi/h. A swimmer attempting to cross the river heads due east swimming at 3 mi/h relative to the wat
Dafna11 [192]

Answer:

<u>velocity of swimmer relative to ground = 3 i -5 j</u>

Explanation:

  • To cross a river the swimmer swims relative to river in perpendicular direction.

Velocity of river = -5 j (south)

Velocity of swimmer relative to river = 3 i(north)

So

<h2>Velocity of swimmer relative to ground = Velocity of swimmer relative to river + Velocity of river</h2>

Velocity of swimmer relative to ground = 3 i -5 j

So magnitude of total velocity is \sqrt{3^2+(-5)^2} =\sqrt{9+25} = \sqrt{34}

3 0
3 years ago
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