# Pythagorean Theorem and Pendulums

1. Jun 7, 2007

### Soley101

1. The problem statement, all variables and given/known data
Calculate the maximum speed of the 100 g pendulum mass when it has a length of 100 cm and an amplitude of 50cm. sorry my computer won't access the other thread. i don't know any other laws of conservations of energy or trig very well. also, when the pendulum as an amplitude of 50 cm , how does this lend me knowledge.

2. Relevant equations
pythagorean theorem (i would like to use this).
a=9.8 m/s2
what does amplitude mean, the pendulums height, or how far the pendulum is from its maximum speed point

3. The attempt at a solution
max of pendulum is at bottom.
pendulum starts gainig speed of a from top till reaches bottom.

2. Jun 8, 2007

### Staff: Mentor

I assume that this means the pendulum mass reaches a height of 50cm above the lowest point.

Hint: Consider conservation of mechanical energy.

3. Jun 8, 2007

### esalihm

you cannot solve this problem without using pythagorean theorem, so don't worry
the amplitude of a pendulum is the displacement of the bob from the equilibrium position. it is not the arc length or anything, it is the displacement.

first draw a figure and call one of the distances you don't know x
then write the others in terms of x

then, u will need to solve a quadratic which u will form by using pythagorean theorem. and u will get 2 values for x. which one do you think is more reasonable to use?

when u get x, construct an equation concerning conservation of energy. think about what the maximum speed impilies

then solve your equation to get the max. speed

4. Jun 8, 2007

### esalihm

the amplitude of a pendulum is defined to be the displacement from the equilibrium position

5. Jun 8, 2007

Good point!

6. Jun 9, 2007

### esalihm

Soley101 did u get the answer?