Calculating Distance Slid on Ground with Friction | Baseball Player Example

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In summary, the problem involves a baseball player sliding into third base with an initial speed of 7.9 m/s and a coefficient of kinetic friction between the player and the ground of 0.41. The goal is to determine the distance the player slides before coming to rest, but the only given information is the coefficient of friction. Using Newton's second law and the equation for kinetic friction, the player's mass can be represented as 'm' and will ultimately cancel out of the equations. Another approach could involve using the work energy theorem, which states that the kinetic energy lost by the player is equal to the work done sliding against friction.
  • #1
Confused too
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Homework Statement



A baseball player slides into third base with an initial speed of 7.9 m/s. If the coefficient of kinetic friction the player and the ground id .41, how far does the player slide before coming to rest

Homework Equations



vf^2=vi^2 + 2ad
kf=μm

The Attempt at a Solution


I tried subsituting but I need acceleration and distance. I didn't know where to go from there
 
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  • #2
Are you given mass of the baseball player?
 
  • #3
Ace. said:
By kf=μm do you mean Fk = μk x FN?

Note that FN is the normal force which in this case is equal to force of gravity.

This equation may also be of use to you : a = FUN / m

sorry, yeh you're right with the formula

but why is the normal force equal to gravity and what is FUN
 
  • #4
Sorry, do you have mass?
 
  • #5
No, no mass is given
 
  • #6
Confused too said:
I tried subsituting but I need acceleration and distance.
Use Newton's 2nd law to find the acceleration. The only force acting (at least horizontally) is friction.

Just call the mass 'm'. You won't need an actual value.
 
  • #7
Doc Al said:
Use Newton's 2nd law to find the acceleration. The only force acting (at least horizontally) is friction.

Just call the mass 'm'. You won't need an actual value.

I don't understand. F=ma so a=F/m but we don't have an F. I don't really understand frictional forces at all
 
  • #8
Welcome to PF!

Hi Confused too! Welcome to PF! :smile:
Confused too said:
A baseball player slides into third base with an initial speed of 7.9 m/s. If the coefficient of kinetic friction the player and the ground id .41, how far does the player slide before coming to rest
Confused too said:
I don't really understand frictional forces at all

You have the coefficient of frictionk = 0.41) …

so if the mass is m, what is the friction force? :wink:

(btw, you can then use the work energy theorem)
 
  • #9


tiny-tim said:
Hi Confused too! Welcome to PF! :smile:

thanks :smile:

You have the coefficient of frictionk = 0.41) …

so if the mass is m, what is the friction force? :wink:

(btw, you can then use the work energy theorem)

But we're not given m and what's the work energy theorem?
 
  • #10


Confused too said:
But we're not given m
So create an unknown for it (m?) and with luck it will cancel out of the equations later.
and what's the work energy theorem?
In this case, that the kinetic energy lost by the player is equal to the work done sliding against friction. But you might as well stick with the equations you quoted. (The second one is more accurately written kf=μmg.)
 

What is friction?

Friction is a force that opposes motion between two surfaces in contact with each other. It is caused by the irregularities and roughness of the surfaces, which create resistance when they come into contact with each other.

What are the types of friction?

There are three main types of friction: static friction, kinetic friction, and rolling friction. Static friction occurs when two surfaces are not moving relative to each other. Kinetic friction is the force that opposes the motion of two surfaces that are sliding against each other. Rolling friction is the force that opposes the motion of an object rolling on a surface.

How is friction measured?

Friction is measured using a unit called a coefficient of friction, which is a ratio of the force needed to move an object over a surface to the weight of the object. The higher the coefficient of friction, the greater the amount of friction between the surfaces.

What factors affect friction?

The amount of friction between two surfaces is affected by several factors, including the nature of the surfaces (smooth or rough), the force pushing the surfaces together, and the type of motion between the surfaces (sliding, rolling, or stationary).

How can friction be reduced?

Friction can be reduced by using lubricants, which create a layer between the surfaces and reduce the resistance. Smoother surfaces can also reduce friction, as well as reducing the force pushing the surfaces together. In some cases, changing the type of motion between the surfaces can also reduce friction.

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