# Phiscis Paper 1

#### 1992

Can anyone explain these 4 questions please
Its from M/J 2003: Q3, Q20, Q30, Q40

#### intel1993

Q3) very similar to mechanics concepts..
horizontal component = 10-10cos60

vertical= 10 sin 60

(10sin60)^2 + (10-10cos60)^2= R^2

solve it u will get ur ans.............

#### intel1993

in this question avverage current concept would be applied as in average velocitty.....

eg: u+v/2 = s/t
same here...
current 1 + cuurent 2 /2 = charge /time

100+20/2 = charge/8

charge= 480... C is ans...

#### azfar kashif

Remember this! Whenever 2 equal forces of whatever equal magnitude have an angle of 120 like in this Q3, the resultant is equal to the individual forces!!!!

#### azfar kashif

For Q.40, u know that a proton has a charge of +1

In this case: the answer is D! why?
because..........
2 upquarks means 2*(2/3e). in this, add 1 down quark which means 1*(-1/3e)

Adding both, u'll get 1!!! I had to try this 4 all combinations before reaching to the correct optioN!!! Tricky one

#### azfar kashif

Can someone plz tell me how 2 solve Q22 of the same paper? (J03/P1)

Find the K for one spring..

F=ke

Since the force divides up equally on all three K = W/3x

Now in the next part there are two springs and the force is of 2W. the force on one spring is W.. the extension =F/K
e= W/(W/3x) which gives the ans D ..3x

#### musa

yar why should we use load w why not 2w when calculating the extension

#### musa

ok i understood why using w thanks