Friction and Traction.

Question 1

friction

Answer 1

the force that opposes the movement of two surfaces that are in contact with one another.

Question 2

two types of friction

Answer 2

force locking - between two smooth materials
form locking - material properties of traction. ( the nature of the surfaces) the coeffcient of friction descrives this relationship.

Question 3

difference between Us and Uk

Answer 3

Us sets the limit for when sliding begins. if the force exceeds uFN , the object will start to slide. Once sliding has occured Uk governs the resustance to ongoing motion.

Question 4

if u > 1

Answer 4

then Fh must be very high to overcome the normal force.

Question 5

if u < 1

Answer 5

then sliding may occur with Fh less than Fn.

Question 6

what is weight on an object and what can it be split into

Answer 6

this is the force due to gravity, parallel and perpendicular.

Question 7

what is the parrallel component of weight.

Answer 7

this pulls the object down a possible slope it is on. this can be responsible for initiating motion. (W II).

Question 8

what is the perpendicular component of weight.

Answer 8

this presses the object against the surface of the incline and determines the normal force (Fn)

Question 9

what advantage would it give a player if they push up and forward to make a tackle.

Answer 9

offsetting the perpendicular component to give themselves more of an advantage over the players normal force given they both have the same coefficient.

Question 10

what do surfaces with greater translational and rotational resistance between the shoe and surface have higher risks of?

Answer 10

higher knee and ankle joint moments. ACL, ankle, long term degeneration, tendinopathy and osteoartgritis.