Question

James pulls a sled with a mass of 80kg across his lawn. He pulls with 150N of force. a) Determine the force of friction if the acceleration is 0.5m/s2. b) What is the coefficient of friction?

 

Answer 1

a)

$F-F_{fr}=ma,$

$F_{fr}=F-ma=150-80\cdot 0.5=110~N,$

b)

$F_{fr}=\mu N=\mu mg,$

$\mu=\frac{F_{fr}}{mg}=\frac{110}{80\cdot 9.8}=0.14.$