The net weight of the balloon must be zero.
The forces acting on the hot-air balloon when it hovers at a fixed altitude are gravitational force and the upthrust of the hot air. As the balloon is at a fixed altitude, the two forces balance each other resulting in zero net force. Thus, the weight of the balloon is balanced by the upthrust, so the balloon is weightless at this time of the flight.
Wave speed (m/s) = frequency (Hz) x wave length (m)
=0.2 x 100= 20m/s
Answer:
C. tiny particles called charges flowing through the wires.
Explanation:
<h3> Hello!</h3>
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume.
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<span>The most common method in removing debris and living
organisms is through a series of sedimentation and heat application. The role
of sedimentation is to use gravity in separating drinkable water and visible
debris. While treating water with heat kills the living organisms.</span>