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## Homework Statement

A car at the Indianapolis 500 accelerates uniformly from the pit area, going from rest to 320km/h in a semicircular arc with a radius of 200 m. Determine the tangential and radial acceleration of the car when it is halfway through the arc, assuming constant tangential acceleration. If the curve were flat, what coefficient of static friction would be necessary between the tires and the road to provide this acceleration with no slipping or skidding?

**The attempt at a solution**

I solved for tagental acceleration :

At= vf^2- Vo^2 /2d

= 88.8^2/2(pi * 200)

=6.288 m/s^2

For the radial acceleration is :

Ac= v^2/r

=88.8^2/200

=39.5 m/s^2

The correct answer is 19.75m/s^2

Why am I getting it wrong (the radial acceleration)? :/

88.8 is in m/s btw (from the 320 km/h)