Answer:
μ = 0.41
Explanation:
The deceleration of the box can be calculated from the equations of motion
u = initial velocity of the box = 20 m/s
v = final velocity of the box = 0 m/s (since it comes to a stop)
t = 5.0 s
a = ?
v = u + at
0 = 20 + 5a
a = - 4 m/s² (minus sign because of deceleration)
The frictional force, Fr, that stops the box is the same force that causes this deceleration
That is,
Fr = ma
But also, Fr = μN = μmg
μmg = ma
μg = a
μ = (a/g)
μ = (4/9.8)
μ = 0.41
Hope this helps!!
