Answer:
Speed = 0.296m/2
Period = 0.203 s
Explanation:
If by 'long' you mean the wavelength of the waves, then the wavelength
.
The frequency
of the waves is 14.8 waves every 3 seconds or
.
Now the relationship between wavelength
, frequency
and speed
of the waves is:

We put in the values
and
and get:
Now the period
is just the inverse of the frequency, or


Answer
given,
cooling fan revolution = 850 rev/min
fan turns before revolution = 1500 revolutions


θ = 1500 revolution
θ = 1500 x 2 x π
θ = 9424.78 rad
a) using equation of rotation
ω² = ω₀² + 2 α θ
ω = 0 because body comes to rest
0 = 89² + 2 x α x 9424.78
α = -0.42 rad/s²
b) time take for the fan to stop
ω = ω₀ + α t
0 = 89 - 0.42 t

t = 211.9 s
A: Some physical properties change, but the substance keeps its identity.

The rate of change of velocity per unit time is called acceleration.
Its SI unit is m/s².

Explanation:
∆x=300 m×2
∆t=1.5 s
v=∆x/∆t → v=2×300/1.5 = 400 m/s