Question 1
Draw 5 forces - 3 downwards ( 160N , 20N and 50N) , tension and reaction at hinge R (or components of Rx and Ry)
i) Take moments about hinge, T = 80 N ( Tsin60 comp. is used when taking moment)
ii) Summation of forces vertically and horizontally gives :
Rx = 39.9 N and Ry = 161 N
Using Pythagaros th. R = 166N and angle =76 degrees.
Question 2
i)Loss in PE = mgh + 0.785 J
ii) Gain in EPE ( EPE stored) = 0.5kx*2 = 0.392J
iii) Loss in GPE is not equal to gain in EPE because energy is dissipated as heat energy.
Question 3
a) pressure at 0.4m = Patm + hpg = 1.05 x 10*5 Pa
b) Archimedes principle does not mean object is floating!
c) Three forces: Upthrust and Drag force(up) and Weight
cii) U = 0.08 N
ciii) U + F = W (U and W has the same formula but one uses density of fluid and one density of solid)
F = 0.55 N
