Question

A team of eight dogs pulls a sled with waxed wood runners on wet snow (mush!). The dogs have average masses of 19.0 kg, and the loaded sled with its rider has a mass of 210 kg.
(a) Calculate the acceleration starting from rest if each dog exerts an average force of 185 N backward on the snow.
(b) What is the acceleration once the sled starts to move?
The coefficient of kinetic friction is 0.1 and static friction is 0.14

Answer 1

Answer:

a) a = 3.29 m/s²

b) a = 3.51 m/s²

Explanation:

mass of dogs = 19 kg

loaded sled mass = 210 Kg

a)writing all the forces in x direction

$\sum F_x=8F_d-f_{s(max)}= (m_s+8m_d)a\\a=\dfrac{8F_d-\mu_sm_sg}{m_s+8m_d}\\a=\dfrac{8\times 185-(0.14)(210)(9.81)}{210+8(19)}$

a = 3.29 m/s²

b) acceleration  when sled start to move the friction will now be acting will be kinetic friction.  

$a=\dfrac{8F_d-\mu_sm_sg}{m_s+8m_d}\\a=\dfrac{8\times 185-(0.1)(210)(9.81)}{210+8(19)}$

a = 3.51 m/s²