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Answer:
Explanation:
The distance between successive wave crests at sea is 20 m. The boat descends from the crest of the wave, rises and reaches the highest position again within 5 s. Calculate the wave propagation speed.
Given that,
The distance between two successive crest is 20m
Wavelength is the distance between two successive crest or trough
Then, it's wavelength is λ = 20m
The time to reached the maximum height is 5seconds, then it will take (5×4) to complete one period
Then,
Period T = 20seconds
From wave equation
v = fλ
Where
v is speed
f is frequency and
λ is wavelength
The frequency is related to the period
f = 1 / T
Then,
v = λ / T
So, v = 20 / 20
v = 1 m/s
The speed of propagation of the wave is 1m/s
To Polish
Jeśli się uwzględni,
Odległość między dwoma kolejnymi grzebieniami wynosi 20 m
Długość fali to odległość między dwoma kolejnymi grzebieniami lub dolinami
Zatem jego długość fali wynosi λ = 20 m
Czas do osiągnięcia maksymalnej wysokości wynosi 5 sekund, a następnie ukończenie jednego okresu zajmie (5 × 4)
Następnie,
Okres T = 20 sekund
Z równania falowego
v = fλ
Gdzie
v to prędkość
f oznacza częstotliwość, a
λ jest długością fali
Częstotliwość jest związana z okresem
f = 1 / T
Następnie,
v = λ / T
Zatem v = 20/20
v = 1 m / s
Prędkość propagacji fali wynosi 1m/s
a The kinetic energy of an object always has a positive value.
Explanation:
The kinetic energy of an object is the energy possessed by an object due to its motion, and it can be calculated as
where
m is the mass of the object
v is its speed
Let's now analyze each statement:
a The kinetic energy of an object always has a positive value. --> TRUE. In fact, the mass of the object is always positive, and the term is always positive as well, so the kinetic energy is always positive.
b The kinetic energy of an object is directly proportional to its speed. --> FALSE. Looking at the formula, we see that the kinetic energy is proportional to the square of the speed, .
c The kinetic energy of an object is expressed in watts. --> FALSE. Watts is the units for measuring power, while the kinetic energy is measured in Joules, the units for the energy.
d The kinetic energy of an object is a quantitative measure of its inertia. --> FALSE. The inertia of an object depends only on its mass, not on its speed.
e The kinetic energy of an object is always equal to the object’s potential energy. --> FALSE. The potential energy depends on the altitude from the ground, not from the speed, so the two energies can be different.
Learn more about kinetic energy:
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