48 If F, FN and f denotes the magnitude of the contact force , normal force and the frictional - Science - Force and Laws of Motion

Question

48   I f   F ,   F N   a n d   f   d
e n o t e s   t h e   m a g n i t u d e   o f  
t h e   c o n ta c t   f o r c e   ,   n o r m
a l   f o r c e   a n d   t h e   f r i c t i o
n a l   f o r c e           e x e r t
e d   b y   a   o b j e c t   p l a c e d
  o n   t h e   o t h e r   s u r f a c e
  i n   c o n t a c t   Í f   F = 5 N ,
  F N = 20 N   a n d   f = 2 N ,    
    t h e n   t h e   b o d y   w i l l a
  m o v e   i n   f o r w a r d   d i r e c t i
o n                  
                 
      b   m o v e   i n   b a c k w a
r d   d i r e c t i o n c   b e   i n   t h e
  s t a t e   o f   r e s t      
                 
                 
                  d
  b o t h   a   a n d   b 49   I f  
F   ,   F N     a n d   f   d e n o t
e   t h e   m a g n i t u d e   o f   t h e
  c o n t a c t   f o r c e   ,   n o r m a l
  f o r c e   a n d   t h e   f r i c t i o n a
l   f o r c e             e x e
r t e d   b y   a   o b j e c t   p l a c e d
  o n   t h e   r o u g h   h o r i z o n t a l
  s u r f a c e   i n   c o n t a c t   I f
  F = 2 N   ,     F N = 20 N   a n d
  f = 5 N ,         t h e n   t h e
  b o d y   w i l l a   m o v e   i n   f
o r w a r d   d i r e c t i o n        
                 
                b   m
o v e   i n   b a c k w a r d   d i r e c t i o n c
  b e   i n   t h e   s t a t e   o f
  r e s t              
                 
                 
          d   b o t h   a  
a n d   b

Deepak Kumar · Accepted Answer

Dear Student

A body will move forward only when contact force or applied force
is greater than frictional force

Normal force is balanced by the weight of the object

So according to values provided by you the block will not move
forward, it will remain at rest

Regards