Random Flashcards
When it says max per unit length, how to calculate it
Need to actually divide them by each other !
What orientation of forces provides the smallest force needed for EQUILIBRIUM
If they’re OPPOSITE EACH OTHER ! As if wrangled in any other angle, then there is X and Y, and thus need more force to make EQUILIBIRUM
When there is a traingle if forces WHATS easier way ti find angles
Need to make it a triangle and USE SIN RULE / COSINE RULE!
For a triangle of forces, what must be the lengths of the sides,
Specific
The length of two sides must be BIGGER than other side!
Not EQUAL TO MUST BE BIGGER
When it says find the range of angle, what to do?
Take the limit as it goes to 0, and infinity, and when Infinity ONLY CONSIDER THE COEFFICIENTS
What does the reaction force always act
It acts PERPENDICUALR to whatever it’s directly IN CONTACT WOTH
- if directly in contact with rim then yeah perpendicualr
- but it DIRECTLY IN CONTACT with edge then it will be perpendicualr to that rather than rim
Why did more work done sand dune
Beta sue sand would be moved as he walked up so more work done overall
What does having no power mean DONT LACK
This means DRIVING FORCE MUST BE 0!!!
Can’t be equal to resistance either , as then there would be power
General maths , if you have somehting = somehting sin + cos / somehting cos + sin?, how can you solve for angle?
Multiply and collect like terms
If you ONLY HAVE SIN AND COS and the theta is the same, you can DIVIDE through by one because it’s impossible for theta to exist where sin and cos both =zero
Then get tan and find angle!
DONT LACK YOU ALWYWD LACK HERE
Reminders about power
When velocity is cinstsnt, o resultant force, thus power driving force = resultant force
Power force is ALWAYS the driving, don’t lack
Also when speed increase say to accelrwtion and power cinstsnt, this means the driving force will decrease, until the force = resistance, and no more accelrwtion, this is max speed power csn produce
When two things collide, how to find out the time of collisons and the distance travelled by each
Make two equations. The time to collide WILL BE THE SAME, and the distance can be expressed as a SAME VARIABLE
Can thus do simulatenoud
So when colliding what’s always the same
Time of collisons obviously , which you messed up
And the distances can be expressed as 1- x and x
Two variable,s simualtneously solve
FOR TWO TRIANGLES WITH MAX HEIGHT THE SAME, how to compare their areas (easy gcse )
Same heights, means ANYWHERE ACROSS THE TRIANGLE , can do half base times height to find area of new
Don’t lack
