Answer:
Velocity, v = 0.239 m/s
Explanation:
Given that,
The distance between two consecutive nodes of a standing wave is 20.9 cm = 0.209 m
The hand generating the pulses moves up and down through a complete cycle 2.57 times every 4.47 s.
For a standing wave, the distance between two consecutive nodes is equal to half of the wavelength.

Frequency is number of cycles per unit time.

Now we can find the velocity of the wave.
Velocity = frequency × wavelength
v = 0.574 × 0.418
v = 0.239 m/s
So, the velocity of the wave is 0.239 m/s.
Its smallest when the substance is a gas
Answer:
22m/s
Explanation:
Mass, m=60 kg
Force constant, k=1300N/m
Restoring force, Fx=6500 N
Average friction force, f=50 N
Length of barrel, l=5m
y=2.5 m
Initial velocity, u=0

Substitute the values

m
Work done due to friction force

We have 
Substitute the values


Initial kinetic energy, Ki=0
Initial gravitational energy,
\
Initial elastic potential energy


Final elastic energy,
Final kinetic energy, 
Final gravitational energy, 
Final gravitational energy, 
Using work-energy theorem

Substitute the values






Answer:
W = 3.4x0³ J.
Explanation:
The work done by the man is given by the following equation:
(1)
<em>where W: is the work, Ft is the total force and d: is the displacement = 4.25 m.</em>
We need to find first the total force Ft, which is:

<em>where Fm: is the force exerted by the man = 535 N, W: is the weight = m*g*sin(θ), m: is the mass of the man, g: is the gravitational acceleration = 9.81 m/s², and θ: is the angle = 20.0°. </em>

Hence, the work is:
Therefore, the work done by the man is 3.4x10³ J.
I hope it helps you!