A curling stone is moving at a velocity of 8 m/s stops after sliding 5 m across a surface that has 70 N of friction. What is the stone’s mass?

Answer 1

work to stop ... 5 m * 70 N = 350 Joules
... this equals the initial K.E.

K.E. = 1/2 m v^2

350 = 1/2 * m * 8^2 ... m is in kg

Answer 2

V^2 = Vo^2 + 2a*d = 0
8^2 + 2a*5 = 0
a = -6.4 m/s^2.

Mg = M*9.8 = Wt. of stone.
M*9.8 - 70 = M*a
9.8M-70 = -6.4M
16.2M = 70
M = 4.3 kg.