Need assistance with some PHYSICS PROBLEMS

ravadongon

OK I've been given a past paper for revision for this years physics exam (I'm 14). There are 3 question I need help with working out Here are the questions

1. Two tugs are pulling on a ship with forces of 1500kgf and 2000kgf respectively, each at angle of 45 degress to the longitudal axis of the ship. Calculate the resultant (magnitude and direction), relative to the larger force.
The thing I need help with is constructing the vector diagrams from the coplanar force diagrams, what forces go where

2. A volkswagen campervan of mass 1.3 tonne is being raised for servicing on a hydraulic hoist in a service station. The diameter of the large piston in the hydraulic system below the vehicle is 24 cm and that of the small piston in the driving cylinder is 2.1cm
(a) With no load on the hoist the pressure in the oil in hydraulic system is approximately atmospheric. When the VW is being supported what is the resulting increase in oil pressure?
(b) What force is being exerted by the small piston on the oil in the driving cylinder?
(c) How far does the vehicle rise when the driving piston moves in 17cm?
I only need help with part (c)

3. A boggedcar is winched out by 2 chains of equal length attached to some point on the car. The chains may withstand a maximum tension of 5 tonne force. Will they overcome the resistance of 70kN if the angle between them is 90 degrees?
Again I don't know how to construct a vector diagram from the info given.

Thanks and hope you can help!

ravadongon

^^^^^bump^^^^^

ravadongon

Help Me!!!!!!!!!!!!!!!!!!!!!!

ApeXaviour

ravadongon wrote:

OK I've been given a past paper for revision for this years physics exam (I'm 14). There are 3 question I need help with working out Here are the questions

1. Two tugs are pulling on a ship with forces of 1500kgf and 2000kgf respectively, each at angle of 45 degress to the longitudal axis of the ship. Calculate the resultant (magnitude and direction), relative to the larger force.
The thing I need help with is constructing the vector diagrams from the coplanar force diagrams, what forces go where

Construct a vector diagram as in bottom right of pic attached.. Using pythagerous you can work out the resultant vector magnitude, sqrt[1500^2 + 2000^2] = 2500kgf
To find the direction, using the same diagram, you just need to find one of the other angles.. eg sin^-1(1500/2500) = 36.87 degrees
Which means it's 8.13 degrees to one side of the longditudional axis.

ravadongon wrote:

2. A volkswagen campervan of mass 1.3 tonne is being raised for servicing on a hydraulic hoist in a service station. The diameter of the large piston in the hydraulic system below the vehicle is 24 cm and that of the small piston in the driving cylinder is 2.1cm
(a) With no load on the hoist the pressure in the oil in hydraulic system is approximately atmospheric. When the VW is being supported what is the resulting increase in oil pressure?
(b) What force is being exerted by the small piston on the oil in the driving cylinder?
(c) How far does the vehicle rise when the driving piston moves in 17cm?
I only need help with part (c)

Does this question require a prior knowledge of hydrolic hoists? I've worked in car garages, and know what they look like, there is not enough info to complete this question as far as I can tell. You would need to know the length of the base of the the hoist. Either that or I don't understand what it's asking.

ravadongon wrote:

3. A boggedcar is winched out by 2 chains of equal length attached to some point on the car. The chains may withstand a maximum tension of 5 tonne force. Will they overcome the resistance of 70kN if the angle between them is 90 degrees?
Again I don't know how to construct a vector diagram from the info given.

This is the same as the first question, construct a vector diagram similar to the one at the bottom right of the pic attached. Pythagarous: sqrt[5000^2 + 5000^2] = 7071kgf resultant vector force which is 69296N or 69kN max tension. So no, at those angles it wouldn't overcome the 70kN resistance.

ravadongon wrote:

Thanks and hope you can help!

Hope I did.

ApeXaviour

Hold on a sec, you're 14? What tests exactly are you studying for?

PhoenixRising

ravadongon wrote:

(c) How far does the vehicle rise when the driving piston moves in 17cm?
I only need help with part (c)

The work done by each piston is the same.

W = F.d

F1.d1 = F2.d2

Where F1, and F2 are the the forces on each piston and d1, and d2 are the distances each respective piston moves. For example, if piston A supports 1000N, piston B supports 2000N, and piston A moves a distance of 0.6m.

1000 x 0.6 = 2000 x d

d = 0.3m So piston B moves 0.3m when piston A moves 0.6m

Apply the same to your problem and you should get the answer.

angeldelight

ApeXaviour wrote:

Hold on a sec, you're 14? What tests exactly are you studying for?

That's what I was thinking, it's not the JC is it??? Nothing like that on it when I did it!

ravadongon

I was studying for an end of year Physics Exam...

BTW Ape thanks for that... That's exactly what I was looking for

ApeXaviour

np man
End of year school physics exam? What year/grade are you in? Are you studying for the leaving cert or is this some extra-curricular physics course?

planck2

The first and third could pass as leaving cert questions, the 2nd could be a really hard A-level question or a college engineering question, but I can't be sure. Anyway stop hounding the lad, fair play to him whatever exam he is doing

Ali Cat

planck2 wrote:

The first and third could pass as leaving cert questions, the 2nd could be a really hard A-level question or a college engineering question, but I can't be sure. Anyway stop hounding the lad, fair play to him whatever exam he is doing

Indeed, though I did A-level maths and physics and this seems less like a physics question and more like one from the mechanics module in math