At the top of a looped section of roller coaster track, the car and rider are completely upside down. Engineers calculated that the car may travel a minimum speed of 14.3 m/s to keep riders from falling out of the car at the top of the loop. What is the radius of the loop? 22.5 m 18.9 m 17.4 m 20.9 m

What is the length x of the side of the triangle below? (hint: use the cosine function)

Consider a hydrogen atom in the ground state. what is the energy of its electron? =e= jj now consider an excited‑state hydrogen atom. what is the energy of the electron in the =5n=5 level? =e5= j

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?