The mass of an electron is 9.1×10^-31 kg the mass of a proton is 1.7×10^-27 kg an electron and a proton or about 0.59×10^-10 m apart in a hydrogen atom. What gravitational force exists between the proton and the electron of a hydrogen atom ?

An athlete swings a ball, connected to the end of a chain, in a horizontal circle. the athlete is able to rotate the ball at the rate of 8.13 rev/s when the length of the chain is 0.600 m. when he increases the length to 0.900 m, he is able to rotate the ball only 6.04 rev/s. (a) which rate of rotation gives the greater speed for the ball? 6.04 rev/s 8.13 rev/s (b) what is the centripetal acceleration of the ball at 8.13 rev/s? m/s2 (c) what is the centripetal acceleration at 6.04 rev/s? m/s2