Answered By John J

F_N=F_g=1000kg X 9.81m/s²=9810Nm/s²

F_app=F_f=u_kF_N

u_k=F_app/F_N=922N/9810Nm/s²

u_k=0.094

Answered By Courtney P

In order to maintain a constant velocity, The for exerted by the team of Qimmiqs fust equal the the force due to friction. F_Q = μF_n =922N

F_n is the normal force and is equal to the force of gravity. F_n = mg = 1000kg * 9.81m/s =9810N

μ=F_Q / F_n = 922N/9810N = 0.094

Answered By Marija J

The sled is already moving at a constant velocity, and for it to keep moving at a constant velocity, forces in the horizontal direction have to be balanced. This means that the force that the dogs exert to pull a sled must be exactly equal to the force of friction.  

Force of friction is equal to the product of the coefficient of  kinetic friction and the normal force, which  is the force of reaction of the surface to the weight of the sled. Since there is no acceleration in the vertical direction, normal force is simply equal to the force of gravity.

Thus, we have t $F_{fr}=\mu_kN=\mu_kmg$F_ƒ r=μ_kN=μ_kmg he force of kinetic friction = coefficient of kinetic friction x normal force = coefficient of kinetic friction  x weight of the sled.

  $F_{fr}=\mu_kN=\mu_kmg$F_ƒ r=μ_kN=μ_kmg 

From this equation, we find that  $\mu_k=\frac{F_{fr}}{mg}$μ_k=F_ƒ rmg  ; and, since  $F_{fr}$F_ƒ r  = 922 N, we find that  $\mu_k$μ_k  = 922 N/(1000 kg) (9.81m/ $s^2$s² ) = 0.0940.

Answered By Negar S

Do you remember to start a movement we need force greater than friction force?  

Dogs started pulling the sled, and they need to keep going with the same speed, right? 

What does that mean ? it means the friction force shall be equal to total forces of dogs right? 

If friction force will be more at some point velocity will be reduced and and if all of a sudden friction will be less dogs move faster.

just remeber yourself walking on a paved and clean of ice pedestrain and all of a sudden you step on ice, what will happen ? you go faster and you will be unbalanced, and you might be toppled  

So :

Friction Force = Friction Coefficient . Weight or 

  $F_{fr}=\mu_kN=\mu_kmg$

 $Ffr=\mu_k\times mg$Fƒ r=μ_k×mg 

 $922\left(N\right)=\mu_k\times1000\left(kg\right)\times9.81$922(N)=μ_k×1000(kg)×9.81 

 $\mu_k=\frac{922\left(N\right)}{1000\left(kg\right)\times9.81\left(\frac{m}{s^2}\right)}=0.0939$μ_k=922(N)1000(kg)×9.81(ms² ) =0.0939 

IMPORTANT NOTE : In physics UNITS are really really important, always double check the units.

Imagine a simple mistake in units can cause a collapse in a building or a bridge. 

Answered By Victor A

In order to find the coefficient of kinetic friction between two surfaces, the horizontal surface method may be used. This is the Horizontal Surface Method:

μ _s   = F_s / N .     Notice that, F = F_s

  F_s = Force of static friction,   μ_s  = coefficient of static friction,   N  = Normal force or the force perpendicular to the contacting surfaces. Just plug the numbers.

Also, there is a 4-min video. This is the link so the student that posted the question can watch.

https://www.youtube.com/watch?v=rmRwwXgzYqQ

Hope the explanation helps. Thanks for posting the question.

Answered By Clifton P

First of all we need to identify the pertinent information. We have a mass, a velocity, and a force. We're told that the velocity is constant which means a net force of zero (F_net = 0). For that to be true, the force the dogs apply must be exactly equal to the force of friction,

F_net = Fapp - F_f  

--> Fapp = F_f

And the force of friction is given as

F_f = µ F_N

Therefore

Fapp = µ F_N      Where F_N is the normal force, ie the force perpendicular to the surface

The normal force is generally written as F_N = mg cosØ, but since our surface is flat (Ø = 0º) cos 0 = 1

So now we have 

F_app = µ mg

rearranging we get

   $µ=\frac{F}{mg}=\frac{922N}{1000KG\cdot\frac{9.81m}{s^2}}=0.094$µ=Fmg =922N1000KG·9.81ms²  =0.094   

Our units cancel nicely, remembering that Newtons(N) are the same as  $Kg\cdot\frac{m}{s^2}$Kg·ms²   (a mass X acceleration, F=ma)