Physics of A Coaster

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…Basically the force of gravity and the force of normal are playing a tug of war and force of normal must win by an amount equal to the net force. At the top of the loop, both forces are directed inwards. The force of gravity is found in the usual way using the equation Fgrav = m*g. Once more the normal force must provide sufficient force to produce the required inward or centripetal net force.