Question

Two forces are such that the sum of their magnitude is 18 N and their resultant is perpendicular to the smallest force and magnitude of resultant is 12N than the magnitude of forces are -
1)12N,6N. 2) 13 N,5N
Questions 2
A lift is moving down with acceleration a.a man in the lift drops a ball inside the lift
The acceleration of the ball as observed by the man in the lift and man standing stationary on the ground are respectively
1)g,g. 2)g-a,g-a, 3)g-a, g 4)a,g
Plzz solve these problems
Explain your answer with correct examination

Answer 1

Q1)
  P and Q are two forces (vectors) inclined at an angle. Let Q be the smaller force.
      P + Q = 18 N
  R is the resultant force vector perpendicular to Q.  and  R = 12 Newtons
   The triangle made by P, Q and R vectors, is a right angle triangle with P as the diagonal and Q and R as sides.
         So    P² = Q² + R²
                 (18 - Q)² = Q² + 12²    =>  Q = 

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  Q2)
       given acceleration of lift = a   downwards
       Acceleration of the ball when it is released by the man in the lift
                   = g - a   wrt the man inside the lift. 
                   = g - 0 = g       wrt the man standing on the ground

When we are looking at velocity v1  or acceleration a1 relative to some other object having velocity v2 and acceleration a2 , then the relative velocity of relative acceleration of the first body wrt the second body is =  v1 - v2    and  a1 - a2  respectively.
         here these quantities are vectors...