I have some questions (or checks) on some problems from a fatty packet our teacher decided to give us for the AP test. If I've already given a possible solution, see if I did it right. Thanks!(adsbygoogle = window.adsbygoogle || []).push({});

Problem 1:

A simple pendulum consists of a mass 1.8kg attached to a string of length 2.3m hanging off a ceiling. A light horizontal string attached to a wall holds the pendulum at an angle of 30* from the vertical.

(a)Draw a free-body diagram.

Tension 1 (T.) - 60* (+y)

Tension 2 (T,) - 0* (+x)

Weight (mg) - 90* (-y)

(b)Calculate the tension in the horizontal string.

Since [T,=T.x], find [T.x] by using trigonometry after finding that [T.y=mg].

(c)The horizontal string is now cut close to the mass, and the pendulum swings. Calculate the speed of the mass at the lowest position.

Here's where I forget what to do. Do I find the period? Then what do I have to do?

Problem 2:

A ball attached to a string of length [L] swings in a horizontal circle with constant speed. The string makes an angle [A] with the vertical, and [T] is the tension. Express your answer with these terms and fundamental constants.

(a)Draw free body diagram.

Tension (T) - A (+y)

Weight (mg) - mg (-y)

(b)Determine the mass of the ball.

Do I use [2(pie)(square root of (l/g))=2(pie)(square root of (m/k))]?

(c)Determine the speed of the ball.

Like the simple pendulum above, I have no idea.

(d)Determine the frequency of the ball.

Since [T=1/f], do I use one of the period equations from part (b)?

This is it (for now). Once again, thanks for your time.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: AP Review Help

**Physics Forums | Science Articles, Homework Help, Discussion**