Six dogs are pulling a sled which is sliding across the snow at a constant speed. The force of friction between the sled and snow is 180N. How much force does one dog pull?

Explanation:

According to the 2nd Newton's Law, a system moving with net force equalized to zero is at rest or moving at constant speed. The total pulling force has the same magnitude than friction force but opposite direction. Let assume that each dog is pulling the sled with the same force, then:

V²=U² + 2as

Where V=Final Velocity

U=Initial Velocity

a=acceleration ( Deceleration in this case)

s=distance covered

10² = 30² + 2(a)(20)

100 = 900 + 40a

100 - 900 = 40a

-800=40a

a= -800/40

a= -20ms-².

Its negative because the car Decelerated.