# Phisic's 12 Help

Problem 1
A 12.0 kg shopping cart rolls due south at 1.50 m/s . After striking the bumper of a car, it travels at 0.80 m/s, 30° E of S. What is the magnitude of the change in momentum sustained by the shopping cart?

a drew a free body diagram used the formula
Pyo + Py1 = P'yo + P'y1 and Pxo + Px1 = P'xo + P'x1
Py1 is some mithical object or the car which i am assumeing isnt moveing im takeing the y direction of its momentom gained + the X direction of its momentom gained adding them together yields
Sqare root of ((12(1.5)-12sin(60)(.8))^2 + (12sin(30)0.8)^2 = 11.8
now heres the problem 11.8 is not an answer what did i mess up? it doesnt seem like a calculator error wheres my thinking wrong?

Problem 2
Diagram = http://quizmebc.ca/images/exams/4010113.gif

x= the object labeled x
C for center of the beam
o for the object on the right
Assume clockwise negative
Sigma t = FxLx + FcLc - FoLo = 0
Rearranged
Lx=FcLc - FoLo / -Fx = 0
(.122)(9.8)(.2) - (.5)(9.8)(.25) / - (.2)(9.8) = Lx
Lx= 1.753 .... hmm considering the length of the entire bar is .9m i think something is wrong...

I'll probally end up have 6 or 7 questions today... i am allowed to ask so many ... dumb questions? (been going through and every 10-15 questions things just dont work right for some very odd reason.)
(big test and no one around for miles that knows theirs a diffrence between mass and wieght...)

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