Answer :
(a)
The work done on the projectile is 9375 joule.
The work on the projectile is calculated as
W=F×d
=1250×7.5
=9375 joule
(b)
The speed of the projectile after 7.5 m is 27.38 m/s
First we need to find out the acceleration of the projectile
F=m×a
1250=25×a
a=50 m/[tex] s^{2} [/tex]
Now the velocity of the projectile after 7.5 m is calculated as
v^2=u^2+2a×s
v^2=0+2×50*7.5
v=27.38 m/s