You are Here: Home >< Physics

# A not so simple harmonic motion question watch

1. A pendulum clock loses 1.5 minutes per day. If the pendulum is 0.85m long, by how much must its length be changed to make the clock run on time?

Kinda confused really, in this case what would the period (T) be and the length, would it be O.85+-X?? Im confused.
2. Shouldn't the period be one optimally, because it should swing once per second?
3. ye... what else can you tell me..
4. T=2pi x root (L/g)

So for the pendulum currently, the time period is 1.8495...

In one day, there are (24x60x60)/T swings = 46715 swings

In a day, 1.5 minutes are lost so 90/46715 seconds are lost per swing = 1.93x10^-3

So, for each swing, the T must be changed by 1.93x10^-3 seconds to make it run on time.

Using the formula, you end up with L=0.851772... or 0.84822... depending on whether you added or subtracted the time (it doesn't matter which)

So you need to change the length by 0.001772m

I'm pretty sure this is right but if anyone has any other ideas, feel free to say.
5. T=2pi x root (L/g)
what equation is it i havnt seen this in my book
doing OCR physics a
6. LaTeX, people.
7. huh?
8. http://www.thestudentroom.co.uk/wiki/LaTex

It makes it much easier to understand what you're asking.

9. (Original post by D-Day)
http://www.thestudentroom.co.uk/wiki/LaTex

It makes it much easier to understand what you're asking.

There's really not much need for LaTeX in this situation, it's quite clear what the quantities are

Purist
10. (Original post by ashy)
There's really not much need for LaTeX in this situation, it's quite clear what the quantities are

Purist
If posting in LaTeX becomes habit for more people, I'll not have to decipher "y=x^2/3+9x-5/2x+17."
11. (Original post by D-Day)
If posting in LaTeX becomes habit for more people, I'll not have to decipher "y=x^2/3+9x-5/2x+17."
Good point.

You just don't need to use latex to type out though

12. is this something i missed in my book? couldnt find it
13. (Original post by ashy)
Good point.

You just don't need to use latex to type out though
Habit. I hardly notice myself doing it anymore
14. (Original post by D-Day)
Habit. I hardly notice myself doing it anymore
You don't notice yourself typing out $blah$ every time?

It's so irritating.
15. lol my thread has been hijacked, jus jokin, thanx for all the help
16. (Original post by SSze)

is this something i missed in my book? couldnt find it
Yes
17. (Original post by D-Day)
Just testing something unrelated.

Woah, your latex is totally narly duude.
18. (Original post by Toxic)
lol my thread has been hijacked, jus jokin, thanx for all the help
Yeah, sorry. Get a couple of geeks together and this is the result...
19. (Original post by D-Day)
Yes
checked twice, no such equation

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 18, 2008
Today on TSR

### 949

students online now

Exam discussions

### Find your exam discussion here

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE