Finding the coefficient of friction (mew) DUE TOMOROW

[newton2008]

Finding the coefficient of friction (mew) DUE TOMOROW :(

Our physics class went curling, and this is the data we had to collect..

Without Sweeping

Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Trial 7
Time (s) 21.37 21.70 21.65 21.95 20.47 20.69 22.30
Distance (m) 115.50 145.50 125.50 112.00 28.00 28.50 261.50

With Sweeping

Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Trial 7
Time (s) 22.06 20.75 24.31 21.50 22.13 21.87 18.15
Distance (m) 147.00 75.50 320.00 18.00 255.00 198.00 42.00

Distances are measured past the second hog line, add 868 inches, and convert to metres.

Mass of Stone = 20 kg (2 sig. digs)
1 ft. = 0.3048 m

One of the question asks to: Calculate the average coefficients of friction with and without sweeping.

So I calculated the Fn = (20)(9.81) = 196.2 N

But the Force of Friction = (mew) * (Fn)

How am i supposed to find the force of friction? So then i can find the (mew)

someone pleaseeeee help

 

[scottie_000]

i suppose you could assume the decceleration due to friction was linear in time so, knowing the final speed, time and distance, you could calculate the decceleration and hence the force using the "vusat" equations