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mezya [45]
3 years ago
9

How much heat is necessary to change 350 g of ice at -20 degrees Celsius to water at 20 Celsius?

Physics
1 answer:
sergejj [24]3 years ago
6 0

Answer:

160790 J

Explanation:

We can find the heat necessary for the ice to go from -20 degrees Celsius to 0 degrees Celsius:

Q=mc\Delta t

Where c=2.09 J/g^{\circ}C is the specific heat of ice, that is the amount of heat that must be supplied per unit mass to raise its temperature in a unit.

Q=(350g)(2.09 J/g^{\circ}C)(0^{\circ}C-(-20^{\circ}C))=14630 J

We must calculate the latent heat of fusion required for this ice mass to change to water:

Q=mH

Where H=334 J/g is the specific latent heat of fusion of water, that is the amount of energy needed per unit mass of a substance at its melting point to change from the solid to the liquid state.

Q=(350g)(334 J/g)=116900 J

Then we calculate the heat necessary for the water to go from 0 degrees Celsius to 20 degrees Celsius:

Q=mc\Delta t

Where c=4.18 J/g^{\circ}C is the specific heat of water, that is the amount of heat that must be supplied per unit mass to raise its temperature in a unit.

Q=(350g)(4.18 J/g^{\circ}C)(20^{\circ}C-0^{\circ}C)=29260 J

Finally the 3 results are added:

Q_{T}=14630 J + 116900 J + 29260 J=160790 J

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Using this formula Vj = V; + at, If a vehicle starts from rest
Furkat [3]

Answer:

<em>The final speed of the vehicle is 36 m/s</em>

Explanation:

<u>Uniform Acceleration</u>

When an object changes its velocity at the same rate, the acceleration is constant.

The relation between the initial and final speeds is:

v_f=v_o+a.t

Where:

vf  = Final speed

vo = Initial speed

a   = Constant acceleration

t   = Elapsed time

The vehicle starts from rest (vo=0) and accelerates at a=4.5 m/s2 for t=8 seconds. The final speed is:

v_f=0+4.5*8

v_f=36\ m/s

The final speed of the vehicle is 36 m/s

5 0
3 years ago
What type of charge will an object have if the object contains less protons than electrons?
Burka [1]

Answer:

Hello, I believe it would have a negative charge considering protons have a positive charge while elctrons have a negative charge

Explanation:

6 0
3 years ago
Assume that a pendulum used to drive a grandfather clock has a length L0=1.00m and a mass M at temperature T=20.00°C. It can be
Sedaia [141]

Answer:

The period will change a 0,036 % relative to its initial state

Explanation:

When the rod expands by heat its moment of inertia increases, but since there was no applied rotational force to the pendulum , the angular momentum remains constant. In other words:

ζ= Δ(Iω)/Δt, where ζ is the applied torque, I is moment of inertia, ω is angular velocity and t is time.

since there was no torque ( no rotational force applied)

ζ=0 → Δ(Iω)=0 → I₂ω₂ -I₁ω₁ = 0 → I₁ω₁ = I₂ω₂

thus

I₂/I₁ =ω₁/ω₂ , (2) represents final state and (1) initial state

we know also that ω=2π/T , where T is the period of the pendulum

I₂/I₁ =ω₁/ω₂ = (2π/T₁)/(2π/T₂)= T₂/T₁

Therefore to calculate the change in the period we have to calculate the moments of inertia. Looking at tables, can be found that the moment of inertia of a rod that rotates around an end is

I = 1/3 ML²

Therefore since the mass M is the same before and after the expansion

I₁ = 1/3 ML₁² , I₂ = 1/3 ML₂²  → I₂/I₁ = (1/3 ML₂²)/(1/3 ML₁²)= L₂²/L₁²= (L₂/L₁)²

since

L₂= L₁ (1+αΔT) , L₂/L₁=1+αΔT  , where ΔT is the change in temperature

now putting all together

T₂/T₁=I₂/I₁=(L₂/L₁)² = (1+αΔT) ²

finally

%change in period =(T₂-T₁)/T₁ = T₂/T₁ - 1 = (1+αΔT) ² -1

%change in period =(1+αΔT) ² -1 =[ 1+18×10⁻⁶ °C⁻¹ *10 °C]² -1 = 3,6 ×10⁻⁴ = 3,6 ×10⁻² %  = 0,036 %

4 0
3 years ago
Which of these is the movement of material cause by the interaction between worm and cool material?
mr Goodwill [35]
Convection Current  
This happens when there is a noteworthy contrast in temperature between two sections of a liquid. At the point when this temperature distinction exists, hot liquids rise and cool liquids sink, and after that streams, or developments, are made in the liquid
7 0
3 years ago
4. If the velocity of the particles is high, they will collide with each other with less force.
tresset_1 [31]

Answer:

7657

Explanation:

3 0
3 years ago
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