1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: A few questions about water pressure, temp, and sound

  1. Jul 5, 2005 #1

    I have done most of them correctly on my own, I need 2 checked and help with one:


    A sound source emits sounds of frequency 210 Hz that travel through still air at 340 m/s. The source moves away from the stationary listener at 80 m/s. Find the wavelength of the sound waves between the source and the listener.

    I got Wavelength =2m

    A small immersion heater is rated at 380 Watts. Estimate how long it will take to heat a cup of soup (assume this is 240g of water) from 23oC to 56oC

    I got t=87.2451s

    Now I need help with this one:

    A 3.8 kg block of copper at a temperature of 79oC is dropped into a bucket containing a mixture of ice and water whose total mass is 1.2 kg. When thermal equilibrium is reached the temperature of the water is 8°C. How much ice was in the bucket before the copper block was placed in it?
    (Neglect the heat capacity of the bucket.)

    I know heat gained=heat lost, so:

    3.8*(79-8)*387(heat capacity of copper) = ?

    I don`t know how to treat the mixture of ice and water. can someone please help me?
    Last edited: Jul 5, 2005
  2. jcsd
  3. Jul 5, 2005 #2
    Please! I truly need help before 10:00!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook