The various properties of electromagnetic waves and sound waves are described below. Sound Waves: Sound waves are mechanical<span> waves generated from vibrations within a medium. Sound can exist as longitudinal </span>mechanical<span> waves, which are also known as compression waves.</span>
Answer:
(E)56.0 m/s
Explanation:
Height =h=-160 m
Because the wallet moving in downward direction
Time=t=7 s
Final speed of wallet=v=0
We have to find the speed of helicopter ascending at the moment when the passenger let go of the wallet.

Where 
Substitute the values



Option (E) is true
Answer:
a) 20 m/s
b) 37.5 m)s
Explanation:
Average speed = total distance ÷ total time
=> (a) average speed of a car that travels 400m in 20s
= 400/20 = 20 m/s
& (b) average speed of an athlete who runs 1500m in 4 minutes (or 4×60=240 seconds)
= 1500/240 = 37.5 m/s
Answer:
The average velocity of a train moving along a straight track if its displacement is 192 m was during a time period of 8.0 s is 24
.
Explanation:
Velocity is a physical quantity that expresses the relationship between the space traveled by an object and the time used for it. Then, the average velocity relates the change in position to the time taken to effect that change.

Velocity considers the direction in which an object moves, so it is considered a vector magnitude.
In this case, the displacement is 192 m and the time period is 8 s. Replacing:

Solving:
velocity= 24 
<em><u>The average velocity of a train moving along a straight track if its displacement is 192 m was during a time period of 8.0 s is 24 </u></em>
<em><u>.</u></em>