Answer:
Convection currents are the result of different heating. Lighter material (warm) rises while heavier (cold) material sinks. This movement of the materials is what causes convection currents! (BTW, it happens in water, in the atmosphere, and in the mantle of Earth!
Explanation:
I hope this helps a little! :)
Answer:

Explanation:
We know that the frequency of the nth harmonic is given by
, where
is the fundamental harmonic. Since we have the values of two consecutive frequencies, we can do:

Which for our values means (we do not need the value of <em>n</em>, that is, which harmonics are the frequencies given):

Now we turn to the formula for the vibration frequency of a string (for the fundamental harmonic):

So the tension is:

Which for our values is:

Answer:
The velocity of the boat with respect to the ground is 3 km/h
Explanation:
The speed of an object is different depending on the reference system you use. This is called relative speed.
A boat travels upstream, this means that it moves in the opposite direction to the river current.
A boat travels upstream, this means that it moves in the opposite direction to the river current. Then, if the boat moves in the positive direction of the x axis at 10 km / h with respect to the water of a river, the water flows in the negative direction of the x axis at 7 km / h with respect to the ground.
This causes the speed of the boat relative to the ground to be calculated as follows:
<em>VbG = Vbw - VwG
</em>
where VbG is the speed of the boat relative to the ground, Vbw is the speed of the boat relative to the water of the river and VwG is the speed of the water relative to the ground.
So: VbG=10 km/h – 7 km/h
<u><em>VbG= 3 km/h
</em></u>
The direction of this velocity is in the positive x-direction.
Answer:
M V = m v conservation of momentum (Caps-cannon Small-projectile)
V = m / M * V = 2 / 2000 * 200 m/s = .2 m/s recoil velocity of cannon
KE = 1/2 M V^2 = 2000 / 2 kg * (.2 m/s)^2 = 40 kg m^2/s^2 = 40 J
car starts from rest

final speed attained by the car is

acceleration of the car will be

now the time to reach this final speed will be



so it required 1.39 s to reach this final speed