Please solve these 2 question in details. I know the answer but don't know how to do.

1. A rocket is fired vertically upward in a vacuum. During the burning process, the fuel mixture is expelled at a constant rate 1431 kg/s and the exhaust gas is ejected at a constant velocity with magnitude 412 m/s. (i) What percentage of the total initial mass M the rocket has to burn in order to accelerate to the speed of 526 m/s? (Answer : 72) (ii) What is the speed of the rocket ( relative to earth) when 21% of its total initial mass M is ejected? (Answal : 97) 2. Let =- 13i - 12j + 18k and v = 3j + 2k be vectors in three space. (i) Find | | v x ull (Answer : 94 ) (ii) A unit vector in the direction of v x u is given by n = a i + bj + ck ( Answer : n = /4 7 - 47 ] + 3/7*)