Does this make sense? Something hanging from an accelerating object

[Cheeseburger]

Homework Statement

A pair of fuzzy dice is hanging by a string from your rearview mirror. While you are accelerating from a stoplight to 28m/s in 6s, what angle does the string make with the vertical?

Homework Equations

g, accel. of car is 4 2/3 m/s^2

The Attempt at a Solution

http://img505.imageshack.us/img505/8594/physwl0.png

I just figured the two accelerations were all that was necessary since the string length and mass are not given. So the angle is arctan(4.66/9.8) or 25.43 degrees? I did this in class in under a minute and it seems right but on the other hand it also seems too easy.

 

[mgb_phys]

Yes it is that easy (assuming your arithmatic is correct)

 

[thomate1]

Yes, your solution is correct. The angle the string makes with the vertical is 25.43 degrees. The acceleration of the car, which is 4 2/3 m/s^2, is the only acceleration acting on the dice and therefore determines the angle of the string. Since the mass and length of the string are not given, they do not affect the angle in this scenario. Good job on solving the problem quickly and accurately!