Question

A 90.1-kg baseball player slides into second base. The coefficient of kinetic friction between the player and the ground is μk = 0.511. (a) What is the magnitude of the frictional force? (b) If the player comes to rest after 1.91 s, what is his initial speed?

Answer 1

the magnitude of friction force = the normal force times the coefficient of kinetic friction.

the normal force in this case is equal to the force of the baseball player

remember force is F = m*a, or force = mass * acceleration of gravity

Answer 2

Thanks though.but what unit should I use for coefficient of frictional force?

Answer 3

good question, but it turns out all coefficients of friction are unit-less, meaning they have no units, they are just a number.

Answer 4

I tried that and nothing worked out. then i tried N cuz it its asking for the coefficient of froction force.do u want me to give u the word to word problem?

Answer 5

A baseball player with mass m = 79.0 kg, sliding into second base, is retarded by a frictional force of magnitude 490 N. What is the coefficient of kinetic friction μk between the player and the ground?
My answer:0.633 and I just need unit.

Answer 6

490 = (kinetic friction) * ( 79 kg * 9.8m/s^2)

yes, 0.633 is correct
there are no units for coefficient of frictions, they are written like this: 0.63

Answer 7

I don't know man. I tried without putting any numbers so it didnt work and then I tried with the Newton (N) unit. still did not work.

Answer 8

maybe i am misunderstanding you question-

are you asking, 'what is the unit for the coefficient of friction?'

Answer 9

THis is the exact question below and I got the answer but I am getting wrong because of the unit.cuz i tried twice but nothing works.
A baseball player with mass m = 79.0 kg, sliding into second base, is retarded by a frictional force of magnitude 490 N. What is the coefficient of kinetic friction μk between the player and the ground?

Answer 10

yes I understand that question, and you had the answer correct: 0.63
there are no units for coefficients of friction, or another phrase is it's 'dimensionless'

wikipedia says: "The coefficient of friction (COF), often symbolized by the Greek letter µ, is a dimensionless scalar value"

http://en.wikipedia.org/wiki/Friction#Coefficient_of_friction

Answer 11

ohh ok may be let me try this µ

Answer 12

I tried " This Answer has no Unit and It works" Thanks for the help though. I really Appreciate it.

Answer 13

Can u help me with other problem pls?