def checkCalcForceExertedByXY(self):
print("Checking calcForceExertedByX and calcForceExertedByY...")
p1 = Planet(1.0, 1.0, 3.0, 4.0, 5.0, "jupiter.gif")
p2 = Planet(2.0, 1.0, 3.0, 4.0, 4e11, "jupiter.gif")
p3 = Planet(4.0, 5.0, 3.0, 4.0, 5.0, "jupiter.gif")
self.checkEquals(p1.calcForceExertedByX(p2), 133.4,
"calcForceExertedByX()", 0.01)
self.checkEquals(p1.calcForceExertedByX(p3), 4.002e-11,
"calcForceExertedByX()", 0.01)
self.checkEquals(p1.calcForceExertedByY(p2), 0.0,
"calcForceExertedByY()", 0.01)
self.checkEquals(p1.calcForceExertedByY(p3), 5.336e-11,
"calcForceExertedByY()", 0.01)
