<span>The Earth’s internal "((HEAT))" source provides the energy for our dynamic planet, providing it with the driving force for on-going disastrous events such as earthquakes and volcanic eruptions and for plate-tectonic motion. </span>
d=18cm=0.18m thickness of board
vi=420m/s speed before entering the board
vf=320m/s speed when leaving the board
vf²=vi²+2×a×d
Acceleration a=(vf²-vi²)/2/d
a=-205.5m/s².
As expected, a is negative because the bullet is decelerated.
vf=vi+a×t
t=(vf-vi)/a=(320-420)/(-205.5)= 100/205.5=0.486s
t=0.486s=486ms
Answer:
α = 1.875 rad/s²
t = 8 s
Explanation:
α = ω²/2θ = 15²/(2(60)) = 1.875 rad/s²
t = ω/a = 15 / 1.875 = 8 s