Physics Help

[Xylitol]

I dont remember how to solve these problems
But can smeone help me

A book sliding across alon ga horizontal table has a constant frictional force of 4 N acting on it. If it has a mass of 1 kg and an initial speed of 8 m/s, how long will it tkae to come to rest?

I know for a lot of you guys thsi is easy, so can you tell me how to do it?

 

[tyler811]

Sorry you lost me at "alon ga horizontal table has a constant frictional force of 4 N"

 

[Xylitol]

anyone?

 

[PurdueRy]

<-Official HW helper of ATOT

This should be right:

F=ma
4 = (1kg)a
a = 4m/s^2

vf = V0 + at
0 = 8m/s + (-4m/s^2)t
t = 2 sec

For distance it will slide:

Vf^2 = V0^2 + 2ax
0 = 64 + 2(-4)x
8x = 64
x = 8 m

 

[hypn0tik]

The best way to start is by drawing a free body diagram. From there you analyze the forces you have and use equations relating the stuff you know.

Also, make sure you properly define the co-ordinate system you choose and be consistent throughout. That'll take care of the signs for you.

 

[Umberger]

how long in distance, or in time?

 

[Fenixgoon]

Originally posted by: Xylitol
I dont remember how to solve these problems
But can smeone help me

A book sliding across alon ga horizontal table has a constant frictional force of 4 N acting on it. If it has a mass of 1 kg and an initial speed of 8 m/s, how long will it tkae to come to rest?

I know for a lot of you guys thsi is easy, so can you tell me how to do it?

F = MA

4 N = 1kg x A

A = 4 m/s^2, v = v0 - at

0 = 8 - 4t

t=2

 

[mackle]

bump for a physics question....I think I can help if I was in my Physics class but after I graduated.....I gave everything back to my prof....you should go ask him... J/K

 

[PurdueRy]

Originally posted by: mackle
bump for a physics question....I think I can help if I was in my Physics class but after I graduated.....I gave everything back to my prof....you should go ask him... J/K

It's been answered...twice...

 

[mackle]

Originally posted by: PurdueRy

Originally posted by: mackle
bump for a physics question....I think I can help if I was in my Physics class but after I graduated.....I gave everything back to my prof....you should go ask him... J/K

It's been answered...twice...

and which is the right answer....??

 

[PurdueRy]

Originally posted by: mackle

Originally posted by: PurdueRy

Originally posted by: mackle
bump for a physics question....I think I can help if I was in my Physics class but after I graduated.....I gave everything back to my prof....you should go ask him... J/K

It's been answered...twice...

and which is the right answer....??

They are both the same??

 

[kukyfrope]

You can find the answer to this problem by having a friend drive at 8m/s down the road and you jump out the window. Use a tape measure to measure the length of blood splatters.

 

[Xylitol]

Originally posted by: PurdueRy
<-Official HW helper of ATOT

This should be right:

F=ma
4 = (1kg)a
a = 4m/s^2

vf = V0 + at
0 = 8m/s + (-4m/s^2)t
t = 2 sec

For distance it will slide:

Vf^2 = V0^2 + 2ax
0 = 64 + 2(-4)x
8x = 64
x = 8 m

Holy crap man you're like 10x smarter than me
I didnt even know how to get the Fpush
I guess 8 m/s push = 8 [N]?