Question

1.A 23 kg box is given a shove across a horizontal surface that gives it an initial speed of 6 m/s. The box is eventually brought to rest by friction. The coefficient of kinetic friction in this example is 0.42. How far does the box go after the shove before it stops?

??? m?

2. A 15 kg box is given a shove across a horizontal surface that gives it an initial speed of 18 m/s. The box is eventually brought to rest by friction. The coefficient of kinetic friction in this example is 0.25. How far does the box go after the shove before it stops?

??? m?

Answer 1

1.

a = acceleration = - g = - 0.42 (9.8) = - 4.12 m/s2

vo = initial speed = 6 m/s

v = final speed = 0 m/s

d = distance traveled

using the equation

v2 = vo2 + 2 a d

02 = (6)2 + 2 (- 4.12) d

d = 4.4 m

2.

a = acceleration = - g = - 0.25 (9.8) = - 2.45 m/s2

vo = initial speed = 18 m/s

v = final speed = 0 m/s

d = distance traveled

using the equation

v2 = vo2 + 2 a d

02 = (18)2 + 2 (- 2.45) d

d = 66.12 m