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.


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

No. When an object is falling in a gravitational field (as the proton is here) is the gravitational potential energy increasing or decreasing?

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