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Ashleykins

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I have two homework questions that I am desperate for some help on. I've posted them on our class discussion page, and I'm on my last attempt. We get three attempts on our homework. The first question deals with SPE and the second deals with latent heat.

#1

You have a copper-beryllium alloy spring of length 0.020 m, spring constant 224.0 N/m. spring-states.png

You pull the block out to xmax = 0.033 m and hold it there. Then you release it. As it moves back toward equilibrium, it passes by position x2 = 0.021 m. Calculate the change in potential energy from xmax to x2.

Type in your answer to the nearest 0.001 Joule of potential energy. Use a - minus sign if the ΔPE is negative. E.g., if your answer is -1.2088 Joules, then type in -1.209.

SPE=1/2kx^2

So I've tried a few different things. I know that k=224.0 For x I subtracted xmax-x2, giving me x=0.012 So the equation would be SPE=(1/2)(224)(0.012)^2 = 0.016 This was marked wrong

My next attempt was a solution I found on our class discussion page which stated the following:

SPE=1/2k(xmax) and then SPE=1/2(k)(x2) then subtract the solution from x2-xmax. This also came out wrong. Please help!

While shopping at Yankee Candle, you notice that the price of their candles ($0.06/g) is increasing at a higher rate than your work income.

You decide to make your own candles and buy 454 g of scented paraffin wax from Amazon.com ($0.02/g). To form the candle in your mold, you have to heat the solid wax from room temperature (297 K) to 330 K. Once you pour the liquid wax into the mold, it must cool back down to room temperature (297 K) before removing it from the mold.

Substance: Paraffin Wax:

Melting Point: 327K

Specific Heat (SOLID): 0.57 cal/g K

Specific Heat (LIQUID): 0.58 cal/g K

Latent heat of fusion: 44 cal/g

CALCULATE: total calories of heat is used for this process before pouring it out?

Type in the numeric part of your answer to the nearest calorie. E.g., if your answer comes in at 88.5 calories, then type 89 in the answer box.

So the first time, I thought maybe it was just a mathematical error so I tried it again. Still wrong. I have no idea what it could be here. This is how I calculated it:

for Q1: (454g)(0.57)(327-297) --> (454)(0.57)(30) =7763.40

Q2: (454g)(44) =18160

Q3: (454)(0.58)(330-327) --> (454)(0.58)(3) =789.96

add them up. 26713.36

Round to nearest whole number -->26713

This HW is due at 9am tomorrow, I've spent an entire weekend on it and I still have a test for another class to study for tonight. I'm like this close to just giving up. PLEASE help me.

For Question 1:

1. Homework StatementFor Question 1:

1. Homework Statement

#1

You have a copper-beryllium alloy spring of length 0.020 m, spring constant 224.0 N/m. spring-states.png

You pull the block out to xmax = 0.033 m and hold it there. Then you release it. As it moves back toward equilibrium, it passes by position x2 = 0.021 m. Calculate the change in potential energy from xmax to x2.

Type in your answer to the nearest 0.001 Joule of potential energy. Use a - minus sign if the ΔPE is negative. E.g., if your answer is -1.2088 Joules, then type in -1.209.

## Homework Equations

SPE=1/2kx^2

## The Attempt at a Solution

So I've tried a few different things. I know that k=224.0 For x I subtracted xmax-x2, giving me x=0.012 So the equation would be SPE=(1/2)(224)(0.012)^2 = 0.016 This was marked wrong

My next attempt was a solution I found on our class discussion page which stated the following:

SPE=1/2k(xmax) and then SPE=1/2(k)(x2) then subtract the solution from x2-xmax. This also came out wrong. Please help!

**Latent Heat. So we've done this equation before 100 times using water and it's been fine. I am not understanding what is going wrong now...**

Question 2:Question 2:

## Homework Statement

While shopping at Yankee Candle, you notice that the price of their candles ($0.06/g) is increasing at a higher rate than your work income.

You decide to make your own candles and buy 454 g of scented paraffin wax from Amazon.com ($0.02/g). To form the candle in your mold, you have to heat the solid wax from room temperature (297 K) to 330 K. Once you pour the liquid wax into the mold, it must cool back down to room temperature (297 K) before removing it from the mold.

Substance: Paraffin Wax:

Melting Point: 327K

Specific Heat (SOLID): 0.57 cal/g K

Specific Heat (LIQUID): 0.58 cal/g K

Latent heat of fusion: 44 cal/g

CALCULATE: total calories of heat is used for this process before pouring it out?

Type in the numeric part of your answer to the nearest calorie. E.g., if your answer comes in at 88.5 calories, then type 89 in the answer box.

**2. So I know that Q=mc(delta t)**[/B]## The Attempt at a Solution

.So the first time, I thought maybe it was just a mathematical error so I tried it again. Still wrong. I have no idea what it could be here. This is how I calculated it:

for Q1: (454g)(0.57)(327-297) --> (454)(0.57)(30) =7763.40

Q2: (454g)(44) =18160

Q3: (454)(0.58)(330-327) --> (454)(0.58)(3) =789.96

add them up. 26713.36

Round to nearest whole number -->26713

This HW is due at 9am tomorrow, I've spent an entire weekend on it and I still have a test for another class to study for tonight. I'm like this close to just giving up. PLEASE help me.

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