When you cut your speed in half, you cut your kinetic energy by times.?

Kinetic energy cuts by 1/4 times in that case

Kinetic energy is proportional to the square of the velocity. When speed is cut by a factor of 2, the kinetic energy is cut by a factor of 2^2 = 4

Your answer is 4

Planet earth has a mass of 5.9726x10²⁴ kg.then: 5.9726x10²⁴ kg=100% of the total earth mass.if the water´s mass=5x10-4 % of the total mass, we can solve this problem by the rule of three.5.9726x10²⁴ %*10⁻⁴ %x=(5.9726x10²³ kg)(5*10⁻⁴  %) / 100 %=2.9863x10¹⁹ kganswer:   the mass of the planet´s water would be   2.9863 x 10¹⁹ kg.