Calculating Required Force for Pushing Metal Blocks | Static Friction Help

[Lily131313]

Homework Statement

[/B]
In an automatic materials handeling operation, metal blocks of 1.5 kg each are pushed one at a time from bottom of a stack six blocks high. If the coefficient of friction is 0.25, determine the horizontal force required to push. There is a figure bellow.

I try to solve but my answer is different the offered solution. Don't know am i wronge or there is mistake in solution. Making me crazyy!

 

[Nidum]

Best to use the homework template .

Anyway - show us what calculations you have done so far .

 

[PeroK]

Welcome to PF. You need to post what you've done.

 

[Lily131313]

Best to use the homework template .

Anyway - show us what calculations you have done so far .

 

[Lily131313]

Sorry for color of paper!

 

[Nidum]

That is very hard to read . Please type out any further workings .

How many block surfaces have friction force acting on them ?

Is normal load the same for each surface ?

 

[Lily131313]

That is very hard to read . Please type out any further workings .

How many block surfaces have friction force acting on them ?

Is normal load the same for each surface ?

 

[gneill]

Sorry for color of paper!

It's also not oriented correctly

There's not many equations on it; It would be better to type them in thus making it easier for helpers to help you (while saving them from going blind and suffering a neck injury from turning their heads sideways to see what you've written )

 

[Lily131313]

That is very hard to read . Please type out any further workings .

How many block surfaces have friction force acting on them ?

Is normal load the same for each surface ?

As you can see on figure, 6 blocks each one 1.5 kg. Bottom one is always pushed meaning for sure after that happens another one will be put on top so that again they are six.

 

[Lily131313]

It's also not oriented correctly

There's not many equations on it; It would be better to type them in thus making it easier for helpers to help you (while saving them from going blind and suffering a neck injury from turning their heads sideways to see what you've written )

I agree, just didn't know it flips the photo. Plus i am on phone not pc. Ill do again.

 

[PeroK]

@Lily131313 You may be misunderstanding! In general, we can only help you by asking questions that guide you in the right direction. So, @Nidum wasn't asking because he didn't know, but because he wanted you to think about that aspect of the problem, as he may have seen where your mistake lies.

 

[Lily131313]

@Lily131313 You may be misunderstanding! In general, we can only help you by asking questions that guide you in the right direction. So, @Nidum wasn't asking because he didn't know, but because he wanted you to think about that aspect of the problem, as he may have seen where your mistake lies.

Ok got ur point! Hm let's try again then!

 

[Nidum]

What I would like to see is a diagram showing what forces you think are acting on the block . You can safely assume that it's six blocks during the pushing out phase and that a new block is only added to the stack at a later time .

 

[Lily131313]

What I would like to see is a diagram showing what forces you think are acting on the block . You can safely assume that it's six blocks during the pushing out phase and that a new block is only added to the stack at a later time .

Exactly. I thought as bottom one is always pushed all mass has to be sum as it is on top of frist one.

Fw= mg= 6*1.5*9.81=88.29 N

 

[Nidum]

How many rubbing surfaces on the block being moved ?

 

[Lily131313]

Exactly. I thought as bottom one is always pushed all mass has to be sum as it is on top of frist one.

Fw= mg= 6*1.5*9.81=88.29 N

 

[Lily131313]

How many rubbing surfaces ?[/QUOTEi

Two up and down. I try that as well again didn't come to right solution.

 

[Nidum]

Draw a free body diagram for the moving block .

 

[Lily131313]

Draw a free body diagram for the moving block .

If we assume that friction is the same up an down 0.25!

 

[Lily131313]

I got it! Thank you!