Question

$guys plz solve this question for me..........$
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Answer 1

initial velocity (u)= 20 m/s

final velocity (v)= 0 m/s

distance covered (s)=50 m

$As per the formula$

v² =u² + 2 as

u² = 2 a s

a= -400/100

a= -4 m/s²

F = u N

F = ma =1×4 =4 N

N= mg =1×9.8 =9.8 N

u =F/N

u=4/9.8

u=0.4

Answer 2

Answer:

4 Newton.

Explanation:

First we will find the value of deceleration of the iron sphere, according to the formula

$v^2=u^2+2as\\\\0^2=20^2+2*a*50\\\\-400=100a\\\\a=-4\,m/s^2$

Now, this deceleration must have came from frictional force, because no other force is present there to stop the ball.

Hence,

∵ $F=ma\\\\F=1*(-4)\,N\\\\F=-4\,N$

-ve sign represents that the force is opposite to the direction of the motion.