# Homework Help: Having trouble calculating Radial and Tangential aspects of a cars acceleration

1. Sep 15, 2011

### nukeman

Having trouble calculating Radial and Tangential aspects of a cars acceleration...!!

1. The problem statement, all variables and given/known data

Here, I will just post the question as an image. Never mind the one where I have to sketch, but b and c I am having trouble with.

How do you calculate the radial and tangential aspects of the cars acceleration? and from that info, how do I calculate the radius?

2. Relevant equations

2. Sep 15, 2011

### LCKurtz

Re: Having trouble calculating Radial and Tangential aspects of a cars acceleration..

You have the tangential direction since you are given the velocity. Figure out the vector projection of the acceleration along the tangential direction and subtract that from the acceleration to get the normal component. From that you should be able to calculate the curvature and radius of curvature with standard formulas.

3. Sep 16, 2011

### nukeman

I'm still having trouble with b

??

4. Sep 16, 2011

### SammyS

Staff Emeritus
Re: Having trouble calculating Radial and Tangential aspects of a cars acceleration..

Method 1:
Write the car's acceleration and its velocity in component form.
Then find the scalar (dot) product $\vec{a}\cdot\vec{v}$ from the components.
Remember that this scalar product gives you the component of a that's in the direction of v times the magnitude of v.
Can you take it from here?​

Method 2:
From the given information, find the angle between the direction of the acceleration and the direction of the velocity.
Use basic trig. to find the component of a parallel to v and the component of a perpendicular to v.​