https://session..masteringphysics.co Physics 201 Spring 2016 mView?assignmentPro
ID: 1425390 • Letter: H
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https://session..masteringphysics.co Physics 201 Spring 2016 mView?assignmentProblemID-59406490 Sliding In Socks previous 2 of 2 return to assignmen Sliding In Socks If Zak's speod is 3.00 m/s when ho starts to slide, what distance d wll he slide before stopping? Express your answer in meters Suppose that the coefficient of kinetic friction between Zak's feet and the floor, while wearing socks, is 0.250. Knowing this, Zak decides to get a running start and then slide across the floor 1.84 Submit My Answer Give Up Correct Part B Now, suppose that Zak's younger cousin, Greta, sees him sliding and takes off her shoes so that she can slide as well (assume her socks have the same coefficient of kinetic friction as Zak's). Instead of getting a running start, she asks Zak to give her a push So, Zak pushes her with a force of 125 N over a distance of 1.00 m If her mass is 20.0 kg, what distance d does she slide after Zak's push ends? Remember that the frictional force acts on Greta during Zak's push and white she is sliding after the push Express your answer in meters. in Give IIn Esergy and CDExplanation / Answer
A) Zak will stop when all of the kinetic energy is lost to friction. And the energy loss from any force is Force times distance.
E(friction) = KE
F(fric) x d = 0.5 m v^2
F(normal) mu d = 0.5 m v^2
m g mu d = 0.5 m v^2
g mu d = 0.5 v^2
d = 0.5 v^2 / g mu
Zak's mass falls out of the equation. Plug in the known velocity, gravitational acceleration, and coefficient of friction.
d = 1.84 m
B) work by you W= 125N*1m = 125 J,
work by friction w=u*m*g*1m = 0.25*20*9.8*1 =49 J;
her kinetic energy W-w =76= 0.5*m*v^2,
hence v=sqrt(2*76/20) = 2.757m/s;
you may do the same way as you did in (A); or;
her kinetic energy is spent on work of friction:
76 = (u*m*g)*x, hence x=76/0.25/20/9.8 =1.55 m
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