Force to topple a block. (moments, centre of gravity)

[Fionn00]

Hi I would greatly appreciate help on this problem.

Homework Statement

Ok so here is the problem

Homework Equations

The Attempt at a Solution

I first tried to work out the moments for the block on the ground with no angle to the ground.
moments about a = .45(35000*g) - 3.2 * f = 0
Where f is the force exerted from the elephant but the answer I got is 4823 whic is not one of the options.

I then thought maybe it was the force at the angle of tipping over but the moments sum to zero at this angle when f is zero so this can't be it.

Thanks for any help.

 

[I like Serena]

I first tried to work out the moments for the block on the ground with no angle to the ground.
moments about a = .45(35000*g) - 3.2 * f = 0
Where f is the force exerted from the elephant but the answer I got is 4823 whic is not one of the options.

I then thought maybe it was the force at the angle of tipping over but the moments sum to zero at this angle when f is zero so this can't be it.

Thanks for any help.

Hi Fionn, welcome to PF!

Your analysis is entirely correct!
And your answer is the right answer.
Answer C would be the closest and will be intended to be the right answer.
It seems your list of answers is slightly off. :(

Note that all the other answers are off by a significant amount or have the wrong unit.

 

[Fionn00]

Hi Fionn, welcome to PF!

Your analysis is entirely correct!
And your answer is the right answer.
Answer C would be the closest and will be intended to be the right answer.
It seems your list of answers is slightly off. :(

Note that all the other answers are off by a significant amount or have the wrong unit.

Thanks for replying.

Are you sure it would be very strange if the list of answers are wrong as it was a previous exam paper.
I agree by the looks of things the answer is c but was my method definitely right ?

 

[I like Serena]

Thanks for replying.

Are you sure it would be very strange if the list of answers are wrong as it was a previous exam paper.
I agree by the looks of things the answer is c but was my method definitely right ?

Imho you method is definitely right!

And if you're still doubting, consider the meanings of the other answers.
They are way off!

 

[Fionn00]

Imho you method is definitely right!

And if you're still doubting, consider the meanings of the other answers.
They are way off!

Ok thanks for your help.

 

[pongo38]

As a matter of interest, I did some experiments with this sort of problem, but not using an elephant. The result did not accord with this simple theory, perhaps because the theory doesn't take account of the need to raise the centre of gravity to obtain a collapse state. The moral is not to believe everything you are told.