3)they are using (0.5+0.5)/50*100=1.7% D
8)air resistance increases until it balances the weight and no net force so acceleration is 0
11)-mu-mu =-2mu D
12)elastic collision so approach speed =separation speed A
14)B take moments about midpoint of s Fs/2+Fs/2=Fs
16)T has to be larges - resolve vertically C
24)Between 1st and 3rd node 1 wave
Between 3 and 5th 1 wavelength
Between 5th and 6th 1/2 wavelength
so 2.5 wavelengths
30/2.5=12 D
28)B sin x=nw/d
so x=sin ^-1(2*3/8)=48.6
48.6-22=26.6
