When a gas is compressed, its particles are pushed closer together so it is more dense.
Explanation:
Since, it is given that one hand completes 3.19 vibrations in 8.46 sec. Therefore, in one second the number of vibrations will be as follows.

= 0.377 vibrations
Hence, frequency (f) = 0.38 Hz
Now, formula to calculate the speed is as follows.
v = 
or,
= 
= 1.57 cm
Thus, we can conclude that the wavelength is 1.57 cm.
Answer:
v = 40 m / s
Explanation:
Let's use the expressions for accelerated motion
v = v₀ + a t
where vo is the initial velocity, at the acceleration and t is the time.
as the body starts from rest its initial velocity is zero
v = 0 + at
let's calculate
v = 8 5
v = 40 m / s