He is moving, kinetic. The truck had to pull a little harder to get him moving.
F = .66 m g
A stuntman is being pulled along a rough road at a constant velocity by a cable attached to a moving truck. The cable is parallel to the ground. The mass of the stuntman is 90 kg. The coefficient of static friction between the road and him is 0.86. The coefficient of kinetic friction between the road and him is 0.66. Find the tension in the cable.
Do we use static, or kinetic friction, or both to find tension? I am confused as to which one to consider.
Thanks!
2 answers
We have to over-come static friction to get the motion started. We have to over-come kinetic friction to keep it going. We use kinetic friction because our system is already in motion.
M*g = 90 * 9.8 = 882 N. = Wt. of stuntman = Normal force, Fn.
Fk = u*Fn = 0.66 * 882 = 582 N. = Force of kinetic friction.
T-Fk = M*a.
T-882 = 90*0,
T = 882 N. = Tension in cable.
t
M*g = 90 * 9.8 = 882 N. = Wt. of stuntman = Normal force, Fn.
Fk = u*Fn = 0.66 * 882 = 582 N. = Force of kinetic friction.
T-Fk = M*a.
T-882 = 90*0,
T = 882 N. = Tension in cable.
t