(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

this question is about a pendulum's speed. the string is 1.0m long, in which r=1m. it says the tension is twice of the bob's weight when the string is vertical, which means when its at the bottom point of the circular motion.

2. Relevant equations

since [tex]F_T[/tex] should overcome [tex]F_g[/tex], so [tex]F_c=F_T-F_g[/tex].

here is how i solve this question:

[tex]F_c=F_T-F_g=\frac{mv^2}{r}[/tex]

[tex]{2F}_g-F_g=\frac{mv^2}{r}[/tex]

[tex]F_g=\frac{mv^2}{r}[/tex]

[tex]g=\frac{v^2}{r}[/tex]

sub in, then v should be equal to about 3.13m/s

3. The attempt at a solution

i got this answer twice, but the teacher said im wrong.

**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: Circular motion vertically

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