Distance travelled whilst decelerating

[voko]

I calculated tractive resistance force as F = 80000 x 0.07 = 5600N
That is just a force, not work done?

Correct.

I know work done is Force x Distance

Correct, too.

but I don't have an actual distance other than the one I calculate in the end

So make it some unknown variable, and solve for it.

 

[gary32]

So make it some unknown variable, and solve for it.

You've lost me now

Please give me a clue or example,

 

[voko]

If force is F, and displacement is s, what is the work of the force?

If the displacement is s along the gradient angle a, what is the elevation in the end? And what is the corresponding potential energy?

 

[gary32]

If force is F, and displacement is s, what is the work of the force?

If the displacement is s along the gradient angle a, what is the elevation in the end? And what is the corresponding potential energy?

Work of the force is F x displacement?

If displacement is s along the gradient a,
The end elevation is Sin8 x s
Corresponding potential energy is 15054400J?

I still am lost, honestly, I am probably as dumb as it gets when it comes to mechanics, you need to dumb things down to my level

 

[voko]

Work of the force is F x displacement?

Use the symbol $s$ for displacement.

If displacement is s along the gradient a,
The end elevation is Sin8 x s
Corresponding potential energy is 15054400J?

This cannot be a number, because the end elevation is $s \cdot \sin a$, where $s$ is unknown. So you have to write that down as a formula.

 

[gary32]

Use the symbol $s$ for displacement.



This cannot be a number, because the end elevation is $s \cdot \sin a$, where $s$ is unknown. So you have to write that down as a formula.

So what now? Also, what was the principle I used to initially work the problem out?

 

[voko]

So what now?

Write the work-energy equation in terms of known and unknown variables, and solve it.

Also, what was the principle I used to initially work the problem out?

Not sure whether there is a particular name to it. FBD analysis and first principles of motion, perhaps.

 

[gary32]

Write the work-energy equation in terms of known and unknown variables, and solve it.

Not sure whether there is a particular name to it. FBD analysis and first principles of motion, perhaps.

There are 2 unknown variables (from what I can see) so I can't see a way for solving it,
I will have to not submit this work and not get the mark as I am away until the day it needs submitting.

Thanks for everyones help, it has been appreciated.

 

[voko]

Which two unknowns do you think you have here?

 

[gary32]

Which two unknowns do you think you have here?

Work done is unknown because that's what I am trying to find and s appears to be unknown, i know you've said s sin but that means nothing to me. Of course this is solvable but I don't have a clue how

 

[voko]

Work depends on s. Just write that down as a formula. Then plug that formula into the energy-work equation. That will eliminate the work as an unknown.

 

[gary32]

Work depends on s. Just write that down as a formula. Then plug that formula into the energy-work equation. That will eliminate the work as an unknown.

Work = F x s
Energy-work equation = F d = (1/2 mv²) - (1/2 mv²)

Energy-work equation = F d = (1/2 x 80000 x 0²) - (1/2 x 80000 x 19.4²)

= -15054400J

d = W/F
d = -15054400J/what force?

 

[voko]

Work = F x s
Energy-work equation = F d = (1/2 mv²) - (1/2 mv²)

This is not what you had in #33.