The speed of sound is about 340 m/s. Assume that when the motion detector emits an ultrasonic pulse, it must detect the reflected pulse before it can emit its next pulse. Assuming that the length of the air track is about 2 meters, what is the maximum number of pulses per second that the motion detector can emit for measuring distance?
Given:
v = 340 m/s
d = 2 m
t = ?
d = vt
t = d / v
t = 2 m / 340 m/s
t = .0058 s
But the question is asking the time in pulses per second which I don't know how to obtain.
3 answers
Two balls are released simultaneously from rest at the left end of tracks A and B as shown below. The only difference between the two tracks is track A has a dip in the middle. The balls are released from the same height, and the tracks have the same length. Which ball reaches the end of the track first?
I think track B would reach the track first since track A has a dip in the middle.
I think track B would also finish first because I have an enormous erection.