Chp 331 So the kunai is thrown by someone who is greater than a character stated to attack at 69.44 m/s, the kunai is also shown to be faster than the eye beforehand. Characters at the start of the series have shown to be able to attack at fte speeds also
average arm length is 70 cm
since he goes up to block it at his eye I will just assume 110 degrees (1.91986 radians)
70cm x 1.91986 = 134.3902cm
Second Scan
Average eye height is 2.35 cm
135px | 2.35cm
80px | 1.48cm
convert to meters
(1.343902) x (69.44) / (0.0148)
S = 6305.4429 m/s (Hypersonic+)