# Homework Help: Period, the Pendulum and Frequency

1. Jul 21, 2006

### alwysnforevr002

If a pendulum is adjusted so that its frequency changes from 10 Hz to 20 Hz, its period will change from n seconds to what?
a. n/4 seconds.
b. n/2 seconds.
c. 2n seconds.
d. 4n seconds

2. Jul 21, 2006

### Kurdt

Staff Emeritus
what are your thoughts so far?

3. Jul 21, 2006

### alwysnforevr002

Well i think they are inversly related therefore i think the answer should be n/2.

4. Jul 21, 2006

### Kurdt

Staff Emeritus
Yes frequency is 1/t so double frequency half the time.

5. Jul 21, 2006

### alwysnforevr002

Great! Thank You so much. If you have a moment I have another question.

A 0.10 kg piece of copper at an initial temperature of 95°C is dropped into 0.20 kg of water contained in a 0.28 kg aluminum calorimeter. The water and calorimeter are initially at 15°C. What is the final temperature of the system when it reaches equilibrium?

For this problem i can only find an equation that solves for the intial temperature. I tried to solve this equation and i got 255 degress C which i know has to be incorrect because if the piece of copper starts at 95 degrees celcius and is put in cooler water it is not going to get hotter but colder.
If you cant/do not wish to answer this question that is perfectly fine but thank you again for you reassurance on my last question!

6. Jul 21, 2006

### Gokul43201

Staff Emeritus
alwys,

1. Try and post questions on different topics in different threads.