Answer:
A vibration or oscillation is a periodically repeated reversal of the direction of movement.
Explanation:
Une vibration ou une oscillation est une inversion répétée périodiquement de la direction du mouvement.
Here is just another definition.
A vibration is periodic back-and-forth motion centerd around it's equilibrium.
Answer:
Average speed in east direction
Explanation:
We have given average speed of the entire trip = 5 km/hr
First the car 4 hours then travels 12 km in 4 hours
So total time of the trip = 4+4 = 8 hours
So total distance traveled in the trip 
As the car travel 12 km in 4 hours to the west
So distance traveled in 4 hour in east = 40 -12 = 28 km
Time in east direction = 4 hour
So average speed in east direction 
Answer:
2.72×10^-7
Explanation:
velocity = frequency × wavelength
2.05×10^8=7.55×10^14 wavelength
wavelength = 2.05×10^8/7.55×10^14
wavelength = 2.72×10^-7