Question

70 kg man pushes a 50 kg man than what is reaction force

Answer 1

It is really interesting question .

everyone think that here we have to use Newton’s 3rd Law e.g., Every action and reaction are of equal in magnitude but directed in opposite direction.

this way answer should be 50N.

means, 50kg man pushed the other man by 50 N force .but it's wrong .

Solve this question by friction concept

GIVEN,

70kg person pushes a 50kg man by a force of 50N .

So, Let force = 50N

now, normal reaction act on 50 kg man = mg

mg = 500N

we know, friction is directly proportional to normal reaction then,

fr = kN ,

k is coefficient of static friction and N is normal reaction.

now, for balancing fr = F

so, 50 = kN

50 = k × 500

k = 50/500

K = 0.1 ,

hence coefficient of static Friction = 0.1

Let F' force act by 50kg man on 70 kg man

then, F' = static Friction act on 70kg man

= coefficient of static friction × normal reaction act on 70 kg man

= 0.1 × 70 × 10 [ g = 10 m/s² ]

= 70N



''hope it's helpful for you''.

Answer 2

force of reaction =(70*a)-(50*a)