Question

A heavy block is slide across a rough floor with an initial speed of 4m/s . it stops moving after 8 secs . if the average resisting force of friction is 10N the mass of the box I kg is

Answer 1

u=4m/s
t=8s
v=0

now , v=u+at
0=4+8a
a=1/2 m/s2  ---(1)

Now F=ma
taking F as frictional force ,
10=m x 1/2
m=20kg

hope this help you:)