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3 years ago

How much heat energy in megajoules is needed to convert 7 kilograms of ice at -9c to water at 0c

Physics

2 answers:

gayaneshka [121]3 years ago

7 0

We can solve this by using the formulas provided to us by calorimetry.

The energy (heat) that is needed to change a given mass of some solid into its liquid form is

E=Lm·m (Where Lm is a specific constant for the material/substance and m is the mass)

Lm for solid water (i.e. ice) is 334 $\frac{Kj}{Kg}$

We can now solve for E

E= 334⋅2 Kj =668Kj

This is the minimum energy required to melt 2 kg of ice. Remember that this energy will in no way change the temperature of the water since every amount of this energy is needed just to melt the solid itself. Even more energy would be needed to increase the end temperature.

Musya8 [376]3 years ago

6 0

The latent heat of fusion of water is 344 j/p.This will take 344x300 or 100200 J to melt the ice. once it melted its at oc

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A billiard ball is dropped from a height of 64 feet. Use the position function s(t) = –16???? 2 + ????0???? + ????0 to answer th

Delicious77 [7]

Answer:

s(t) = -16*t^2 + 64

v(t) = -32*t

a(t) = -32 ft/s^2

v(t) = 64 ft/s ... At impact

Explanation:

Given:-

- The height of the billiard ball t = 0 , h = 64 ft.

- The position function of an object under gravity is given by:

s(t) = -16*t^2 + v_o*t + s_o

Find:-

a. Determine the position function s(t),

b. the velocity function v(t),

c. the acceleration function a(t).

d. What is the velocity of the ball at impact?

Solution:-

- To determine the position function we must initialize our problem and use the given general equation.

- s(t) is the position of the billiard ball from the ground at time t. So when t = 0, then s(t) = h. Hence, we have:

s(t) = s_o = h = 64 ft

- Similarly we know that v_o is the initial velocity of the ball. Since, the ball was dropped we say that the initial velocity v_o = 0. Hence, the position of the ball from ground is given by following expression:

s(t) = -16*t^2 + 64

- To find the velocity expression v(t) we will take the time derivative of the position expression s(t) as follows:

v(t) = d s(t) / dt

v(t) = -16*2*t + 0

v(t) = -32*t ft/s

- Similarly, the expression for acceleration a(t) is given by the time derivative of the velocity expression v(t) as follows:

a(t) = d v(t) / dt

a(t) = -32*t

a(t) = -32 ft/s^2

- The velocity of ball at impact can be determined by evaluating s(t) = 0 and find the value for time t. Then that time t can be substituted in the velocity expression v(t) for final velocity. Or we could use the following 3rd kinematic equation as follows:

v(t)^2 - 0^2 = 2*a(t)*s_o

v(t)^2 = 2*(32)*(64)

v(t) = 64 ft/s

- The ball has a velocity of 64 ft/s at impact!

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3 years ago

What is the answer to this question?

solmaris [256]

Answer:

NA2SO3 is the reactant in the reaction

Explanation:

The substances which take part in a chemical reaction are called reactants

HOPE IT HELPS 

HAVE A NICE DAY :)

XxYourBabyGirlxX2

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