11-71. A particular proton in space is subjected to two fields: a gravitational field (1.30X105 N/kg  toward planet X), and an electric field (2.47X10-4 N/C away from planet X).
 (a) If the proton is released from rest, in which direction will it move?
 (b) After moving 1.50 m, what will be its speed? Use energy methods and assume uniform fields.


ACCUMULATED SOLUTION

FE = qE     Fg =  mg
Fg =  mg = (1.673X10-27 )(1.3X105) = 2.175X10-22 N
FE = qE = (1.602X10-19 )(2.47X10-4) = 3.957X10-23 N


Correct
Fg > FE so it moves toward the planet.


Which statement is correct as the proton moves from position 1 to position 2?
(A)   Gravitational PE (EP) increases, Electrical PE (U) decreases and KE increases
(B)   Gravitational PE (EP) decreases, Electrical PE (U) increases and KE increases
(C)   Gravitational PE (EP) decreases, Electrical PE (U) decreases and KE decreases
(D)   Gravitational PE (EP) increases, Electrical PE (U) increases and KE increases