Please select the correct statement$($s$).($Multiple choices: one or more answers are

correct.$)$

A Since the mechanical impedance of water is much higher than air, shock

waves receive more resistance from the water than that from the aiv. Hence,

underwater blasts travel normally smaller distances before attenuating

sufficiently to be harmless.

In shaped charge weapons, the liners are typically made from metallic

materials with a body$-$centred cubic structure because they can produce

longer and thinner jets when compared with face$-$centred crystaline metals.

C$.$ The size $($crater radius$)$ of the crater varies proportionately with the cube

root of the explosive energy $($charge weight$)$ for underground explosions.

D$.$ Based on the conoegt of Birkhotf's theory, a smaller value of the apex angle

would result in a higher value of the jet velocity. Hence, a conical liner would

produce a higher$-$speed jet than a Norman helmet liner.

E$.$ Based on Gumey's theory, the ratio belween the mass of the case and the

mass of the explosive charge is the anly factor that influence the initial

velocity of the tragments.