All Mechanics DOUBTS HERE!!!

[Saladin]

I think I did not get a single one wrong!! LOL!

[Ghost Of Highbury]

A shopper pushes a supermarket trolley in a straight line towards her car with a force of magnitude 20N, directed downwards at an angle of 15 degrees to the horizontal.

Given the acceleration is 2.4m/s^2, calculate its mass . (I've done this)

Find also the magnitude of the normal contact force exerted on the trolley by the ground (Need help in this)

Thank you.

[astarmathsandphysics]

resolve vertically
upwards force =R
downwards forces=mg+20sin15
now use the mass

[7ooD]

we need m2 doubts sticky!

[Saladin]

Post all your M2 doubts here!

[7ooD]

what does this sign | means i always see in the ms when giving a range and how to know where the Y component and x component of the reaction of the wall on the hinge is acting because in 2005 june q 6 x and y were acting x ----- left    and y up  in 2007 june q 5 it was x ------- right y ---- down  im relly confused about this here is the images of the diagrams

2005 



2007

[egymoha]

In most of the coofficient of restitution questions i see (when they say find the range of value of e ) ,, in the mark scheme and the answers ,, they usually say v1>0 ,, why do they use V1 rather than V2 .

please someone reply

thanks my friend

[Meticulous]

what does this sign | means i always see in the ms when giving a range and how to know where the Y component and x component of the reaction of the wall on the hinge is acting because in 2005 june q 6 x and y were acting x ----- left    and y up  in 2007 june q 5 it was x ------- right y ---- down  im relly confused about this here is the images of the diagrams

2005 



2007

The sign means the modulus; i.e. always positive

and you ALWAYS take Y and X values of the reaction. Even if there's only one, lets see an X component only, then Y will be zero. Therefore, to avoid confusion, always take Y and X components.

[Meticulous]

In most of the coofficient of restitution questions i see (when they say find the range of value of e ) ,, in the mark scheme and the answers ,, they usually say v1>0 ,, why do they use V1 rather than V2 .

please someone reply

thanks my friend

It depends on the question. For example, if there is further collision or not.

[7ooD]

thx a.f but u misunderstood i meant how to kno in which direction does y act and x act cuz as i gave example in the question above one had y acting up and the other had y acting down same thing happened wiz x one was acting left other was acting right thats what i meant

[Meticulous]

thx a.f but u misunderstood i meant how to kno in which direction does y act and x act cuz as i gave example in the question above one had y acting up and the other had y acting down same thing happened wiz x one was acting left other was acting right thats what i meant

Don't worry mate! Put them in the direction you want, up or down ya wadee3

Caues at last, if you put it in the wrong direction, your answer would be in negative, and you would know

[7ooD]

seems wise ostaaaaaz

[egymoha]

It depends on the question. For example, if there is further collision or not.

ok so how do i solve the questions of range of values of e ,, cause i dunno how to solve them ??

how should i think ??

thanks friends

[Meticulous]

To be honest, these questions are tricky. Give me a question from the past paper or book, and I'll show you

[7ooD]

ok look egy for example if he asks when a particle A was moving towards C and rebounds and moves in opposite direction on the same time another particle B was moving same direction as the direction of A when it rebounds so they ask whether A hits B or not this means that A speed should be greater than the speed of B then u put an inequality A greater than B and most of questions they ask to put the speed of A in terms of e and also same thing for B thats an example hope it helps