# Dice Hanging from Mirroe

## Homework Statement

A pair of fuzzy dice is hanging by a string from your rearview mirror. While you are accelerating from a stoplight to 29 m/s in
5.7 s, what angle θ does the string make with the vertical?

## Homework Equations

v_f=v_0+a*t
x_f=x_0+v_0*t+0.5a*t^2
v_f^2=v_0^2+2*a(x_f-x_0)
x-x_0=[(v_0-v+v_f)/2]*2

And just sum of forces=0
F=ma

Note: v_f^2 is final velocity squared

## The Attempt at a Solution

I'm lost because it seems to me that the mass of the dice must be known to solve?

Related Introductory Physics Homework Help News on Phys.org
This is an accelerated frame of reference. You know the direction of the acceleration that the frame has. There is a fictious force and the natural force (gravity), what is the vectorial sum of these two?

Forget about ficticious forces. Draw a picture and a free body diagram. First, solve for acceleration. The tension force acts at an angle, which means a component of tension accelerates the dice. If you do things correctly, mass should cancel out of the equation

A good idea would be to draw a force diagram outside and inside of the car =). To get a frame of reference for which way the dice are accelerating.

They will be accelerating positively or negatively as the speed of the car =).

Also, split this up into two vectors x and y. Once you start to do all the calculations, you'll find that the mass cancels out in the end =).