Un bloque cuya masa es 6kg reposa sobre una superficie horizontal?

A)

Vo = 0

Vf = ?

A = 1, 72 m / s²

t = 4 s

P = mg

P = 6(9, 8)

P = 58, 8

ΣFy = ma

N - P = 0

N = P

N = 58, 8

μ = coeficiente de rozamiento

Fr = Nμ

Fr = (58, 8)(0, 3)

Fr = 17, 64

ΣFx = ma

F - Fr = m a

28 - 17, 64 = 6a

10, 63 / 6 = a

1, 72 m / s² = a

Vf = Vo + at

Vf = 0 + (1, 72)(4)

Vf = 6, 9 m / s

b)

d = Vot + 1 / 2 at²

d = 0 + 1 / 2 (1, 72)(4)²

d = 13, 76 m

c)

Δr = variacion de la distancia

velocidad constante

ΣFx = ma

F - Fr = 0

F = Fr

W = F .

Δr

W = (17, 64)(13, 76)

W = 242, 72 J

d)

Wfr = FΔr cos 180

W fr = (17, 64)(13, 76) cos 180

W fr = - 242, 72 J

e) Wn = W1 + W2 Wn = 242, 72 - 242, 72 Wn = 0.