the moon is 4.0x10^5Km away from earth. if a bomb were to blow up on the moon, how much time would it take for the sound wave to reach the earth ? the speed of sound in air is 343m/s. if it can’t be calculated explain why

Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to: