# Some lovely physics problems which need to be solved! ahh!

1. Nov 9, 2004

### cissablecat23

1a)A simple pendulum is 4.35 m long. What is the period of simple harmonic motion for this pendulum if it is hanging in an elevator that is accelerating upward at 5.90 m/s2?

b)What is the period of simple harmonic motion for this pendulum if it is placed in a truck that is accelerating horizontally at 5.90 m/s2?

2) A large block P executes horizontal simple harmonic motion as it slides across a frictionless surface with a frequency of f = 1.52 Hz. Block B rests on it, as shown in the figure below, and the coefficient of static friction between the two is μs = 0.630.

What maximum amplitude of oscillation can the system have if block B is not to slip?

And another thing.. if we think we can help someone else.. are we allowed to post? Thanks very much

2. Nov 9, 2004

### Tom Mattson

Staff Emeritus
Sure thing, but 'round these parts we don't help folks until they show how they started the problem, and where they got stuck.

*hint hint*

3. Nov 9, 2004

### stunner5000pt

first of all - look at threads and see if everyone is a homework helper or a mentor when they reply.
secondly show us soome work, becasue you need to understand as opposed to just getting an anaswer blindly!

4. Nov 9, 2004

### cissablecat23

i did start...
1)
l=4.35 m
a= 5.90 m/s/s

w^2=g/l
w^2=9.80/4.35
w^2= 2.252873563

then i have to find T.. but i don't know what formula to use...

2) w=2(pie)f
w-2(pie)(1.52 Hz)
w= 9.5504
and i don't know what else to do

5. Nov 9, 2004

### cissablecat23

sorry i'm new.. don't have to be mean

6. Nov 14, 2009

### Relay

Use the formulat T=2*pi*square root(L/g) ; pi=3.1415, L=4.25m, g=9.81m/s^2

For question 1a << details deleted by berkeman >>

For question 1b g=pendulum component of both accelerations. You need to solve this vector. << details deleted by berkeman >>This assumes that the pendulum swings perpedicular to truck acceleration direction. Assuming the alternative makes the question realy difficult.

To find the amplitude you need the speed given by the frequency and the mass which is missing. This problem can't be solved as given.

Good luck.

Last edited by a moderator: Nov 15, 2009
7. Nov 15, 2009

### Staff: Mentor

Welcome to the PF, Relay. Please take care not to do too much of the OP's work for them. We can offer tutorial hints and look for mistakes in the OP's work, but we should not be posting equations for them.

8. Nov 16, 2009

### Relay

OK. Thanks for the info.