A specimen of unknown material with square cross section of dimension $0\mathrm{.}4mm$ and

has a notch of depth $0\mathrm{.}08mm,$ were impacted by hammer $(15kg)$ of brook's

pendulum tester which rotates and falls from a high of $80cm$ to $60cm.$if the result

was exactly as in the figure below:

Determine:

a$)$ The resistance of material to impact load?

b$)$ Impact energy $($practically$)?$

c$)$ Impact energy $($theoretically$)?$

d$)$ Decide whether the material is brittle or ductile?