Which must exist for electric charges to flow?

69. air frictionthe velocity of the satellitea. decreases b. increases c. sometimes increases sometimedecreases d. no effect at all70. the unit of gravitational potential energy isa. jouté b. watt c. newtond. pascal71. which of the following is not influenced by a magneta. cobalt b. copper c. irond. nickel72. one joule of work done in one second by unit positive chargea.1 watt b.1 volt c.1 js d. none73. the most deviated colour of light after passing through a prisea. violet b. red c. green d. yellow4. a coin is placed below a beaker fill with water upto 12 cm isdisplaced by water isa. 9cm b.6cmс.3cmd.7cm

The doctor lands his tardis on a planet whose radius is 1.2x10^7m the acceleration due to gravity is 18m/s^2. what is the mass of the planet

Mr. polifka does a demonstration in science class. he holds an unlit match six inches above a candle flame. after a while, the match bursts into flame.