Answer:
Step-by-step explanation:
Let us find the acceleration of box .
v² = u² + 2as
Putting the values
7² = 3² + 2 a x 14
a = 1.43 m /s²
If coefficient of friction be μ
force of friction = μ mg
= μ x 10 x 9.8
= 98μ
Net force pushing the box
= 85 - 98μ
Applying newton's second law
85 - 98μ = 10 x 1.43
98μ = 85 - 14.3
μ = .72
