Answer:
The answer is 0.47 watts
power is calculated by Work/Time
14/30 =0.46666666 which is approximately 0.47watts
Answer:
The frequency of sound heard by the boy is 1181 Hz.
Explanation:
Given that,
Frequency of sound from alarm 
Speed = -8.25 m/s
Negative sign show the boy riding away from the car
Speed of sound = 343
We need to calculate the heard frequency
Using formula of frequency

Where,
= frequency of source
= speed of observer
= speed of source
= speed of sound
Put the value into the formula

here, source is at rest


Hence, The frequency of sound heard by the boy is 1181 Hz.
Answer:
maximum speed 56 km/h
Explanation:
To apply Newton's second law to this system we create a reference system with the horizontal x-axis and the Vertical y-axis. In this system, normal is the only force that we must decompose
sin 10 = Nx / N
cos 10 = Ny / N
Ny = N cos 10
Nx = N sin 10
Let's develop Newton's equations on each axis
X axis
We include the force of friction towards the center of the curve because the high-speed car has to get out of the curve
Nx + fr = m a
a = v2 / r
fr = mu N
N sin10 + mu N = m v² / r
N (sin10 + mu) = m v² / r
Y Axis
Ny -W = 0
N cos 10 = mg
Let's solve these two equations,
(mg / cos 10) (sin 10 + mu) = m v² / r
g (tan 10 + μ / cos 10) = v² / r
v² = r g (tan 10 + μ / cos 10)
They ask us for the maximum speed
v² = 30.0 9.8 (tan 10+ 0.65 / cos 10)
v² = 294 (0.8364)
v = √(245.9)
v = 15.68 m / s
Let's reduce this to km / h
v = 15.68 m / s (1 km / 1000m) (3600s / 1h)
v = 56.45 km / h
This is the maximum speed so you don't skid