Train Acceleration Calculation: Spider on a Web Scenario

[muktl]

Homework Statement

if given a scenario for example, a spider is hanging down from a thread of spider web on a train, and when the train moves the spider moved 10 dregees
how to find the acceleration for the train? pretend X is the weight of the spider

if you don't understand the question msg back and i can explain better, i just need a general idea of how to do it

Homework Equations

The Attempt at a Solution

 

[PhanthomJay]

Draw a free body diagram of the spider and note all forces acting on the spider (its weight is one of them, what's the other(s))? Then apply Newton's laws.

 

[jsea-7]

The spider is acting like a pendulum ;)