How Do You Calculate Initial Velocity with Kinetic Friction?

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SUMMARY

The discussion focuses on calculating the initial velocity of a baseball player sliding into second base, given a mass of 81 kg and a coefficient of kinetic friction of 0.49. The frictional force was correctly calculated as 389 N. To find the initial velocity, the player’s acceleration must be determined using the equation F = ma, where the net force is solely the frictional force since the player is coming to a stop. The player’s initial velocity can then be calculated using the equation Vo = Vf - at, with Vf being 0 and time given as 1.6 seconds.

PREREQUISITES
  • Understanding of Newton's Second Law (F = ma)
  • Knowledge of kinematic equations (Vo = Vf - at)
  • Concept of kinetic friction and its coefficient
  • Basic algebra for solving equations
NEXT STEPS
  • Calculate acceleration using F = ma with the known frictional force
  • Apply kinematic equations to find initial velocity
  • Explore the concept of net force in motion scenarios
  • Study the effects of different coefficients of friction on motion
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Students in physics, particularly those studying mechanics, as well as educators looking for practical examples of applying kinematic equations and friction concepts.

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Homework Statement



An 81-kg baseball player slides into second base. The coefficient of kinetic friction between the player and the ground is 0.49. (a) What is the magnitude of the frictional force? (b) If the player comes to rest after 1.6 s, what was his initial velocity?

Homework Equations



F = ma, Vo = Vf - at

The Attempt at a Solution



I already got 389 N for (a), now I'm just stuck on (b). Since I have his mass, Vf, and time, all I need is his acceleration to find Vo. I think I have to use F = ma, but I have no idea how to find the horizontal FNET. Ff is 389 N, but since I don't have his forward force, I don't know where to go from here. Thanks for the help!
 
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What makes you think there is a force on him other than the friction force?
 
Oh, so, since he's coming to a stop, there's only a frictional force?
 

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