(a) Given:

Mass of the missile, m = 75 kg and Speed, v = 60 m/s

Therefore, K.E. = 1/ 2 mv^{2} = 1 /2 × 75 × 60 × 60 = 13500 J

(b) Given,

Mass of the missile, m = 75 kg

Acceleration due to gravity, g = 10 m/s^{2} and Height, h = 850 m

Therefore, P.E. = m × g × h = 75 × 10 × 850 = 637500 J

(c) Total mechanical energy of the missile = K.E. + P.E.

= 135000 + 637500 = 7.7 × 10^{5}J

(d) K.E. at the ground = 7.7 × 10^{5}J

K.E. = 1 /2 mv^{2} , Therefore, v^{2} = 2 K.E. / m

Velocity with which missile strikes the ground =143.2 m/s