Graitaional Potential

.         (a)     force (of attraction) on unit mass (at that point in space/at the
surface of a planet) (1)                                                                                        1

  (b)   (i)      (mgh =) 1500 × 40 × 1.5 × 105; = 9.0 × 109 (J)                                           2

(ii)     (larger as) g decreases with height                                                            1

(iii)     v = 2πR/T; = 2π × 2.0 × 107/(4.5 × 103) = 2.8 × 104 m s–1 (2)
½ mv2; = 0.5 × 1500 × (2.8 × 104)2 = 5.9 × 1011 (J) (2)                             4
aliter: F = mv2/R; = mg; so ½ mv2 = ½ mgR;= 6.0 × 1011 (J)