9. A mass has a charge on it. Another small mass with a positive charge is moved away from the first mass, which remains at rest. As the distance increases, what happens to the gravitational potential energy Eg and the electric potential energy Eg? a) E, decreases and ER decreases. b) Eg either decreases or increases depending on the unknown sign of charge, and E, decreases. c) Eg decreases and Eg increases. d) Eg either decreases or increases depending on the unknown sign of charge, and E, increases. e) Eg increases and Eg decreases. 10. Two isolated electrons starting from rest move apart. Which of the following statemetns is true as the distance between the electrons increases? a) The velocity increases and the acceleration is constant. b) The velocity increases and the acceleration is decreases. c) The velocity decreases and the acceleration is constant. d) The velocity increases and the acceleration is increases. e) The velocity is constant and the acceleration is constant. Short Answer - Neatly provide written responses [10 marks] 11. If the density of the Earth were much greater than its actual value, but its radius was the same what would be the effect on the Earth's surface gravitational field strength? Explain. [2 marks] 12. How would the amount of fuel required to send a spacecraft from Earth to the Moon compare with the amount needed to send the same spacecraft from the Moon back to Earth. Explain. (Numerical values not required) [2 marks]