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## Homework Statement

:[/B]A child of mass 40.0 kg is in a roller coaster car that travels in a loop of radius 7.30 m. At point

*A*the speed of the car is 15.0 m/s, and at point

*B*, the speed is 15.6 m/s. Assume the child is not holding on and does not wear a seat belt.

What is the force (in N) of the car seat on the child at point

*B*? (Enter the magnitude.)

## Homework Equations

Fc = [(mv^2)/r]

Fc = ma

## The Attempt at a Solution

:I solved (a) and (c).

I solved (a) by inserting the mass, speed, and radius into the equation [(mv^2)/r] and subtracting by (mass*gravity).

My equation for (b) was [(mv^2)/r * cos30] - mg = [(40*(15.6^2)/7.3*cos30) - (40*9.8) = 762.8 N. That was incorrect. What's improper about my equation? [/B]