Physics P1 tips, anybody?

[halosh92]

19.8-1%
2.02+1%
looks like they added uncertainty to uncertainty

could you be more specific plzz?
isnt there a rule for this?

[mz]

C
5-1=4
error =0.2/sqrt(4)=0.1
this error at either end so C
B wigth it can lift is proportional to X^"
wieght of ant is proportional to volum=X^3
X^2/X^3=1/X

ok thankyou! i understand the second answer, but for the first one, the answer given is B

[mz]

one more
A neutron is in head-on elastic collision with the nucleas of a stationary nitrogen.the mass of a nitrogen nucleas is 14 times that of the neutron.the neutron's velocity after collision is
A. less in magnitude than its initial velocity
B. less in magnitude than the final velocity of nitrogen atom
C. equal to initial velocity but in opposite direction
D. greater in magnitude then its initial velocity

please tell asap

[cockyxrocker]

Is potential energy proportional to the bond flexibility in solids?...
shouldnt it be other way around?