Calculations: i'm really dumb at this stuff?

Question

1.Calculate your mass in kg. Assume that the body consists of hydrogen atoms, each of which has a mass of 1.67*10-27kg. How many atoms are there in your body?

2.A metal rectangular solid has a mass of 5.5kg & dimensions of 10.0cm*15.0cm*20cm. What is the density of the solid in g/cm3?

4.The steel panel of a car door is 1.00m long. Assuming that it expands in the direction as described in the text, what is a safe separation between the door panel and the body of the car that will allow the panel to expand?

5.How much louder is a normal conversation than whispering?

Answer 1

1. Divide your weight in pounds by 2.2 to get your weight (mass) in Kg. Divide that weight by the weight of one atom to get the number of atoms (it's a lot).

2. Multiply length x width x height to get the volume of the solid in cm^3. Multiply the mass in Kg by 1,000 to get the mass in grams. Divide the mass in grams by the volume in cm^3 to get the density.

3. What happened to question 3?

4. Not enough information here to answer the question. Basically, you need to look at the coefficient of linear expansion for steel, estimate the maximum temperature the door would experience, calculate how much it will grow, and allow clearance to accomodate that growth.

5. You would need a table of volume levels for various noises. If you assume that a normal conversation is about 60 Decibels (dB) and a whisper is about 30 dB, then the normal conversation would be PERCEIVED as being about 8 times louder (10 dB = 2x louder perception) but the energy level would be 1,000 times greater (10 dB = 10x energy level).