Consider the apparatus shown in Figure P18.73a, where the hanging object has mass M and the
string is vibrating in its second harmonic. The vibrating
blade at the left maintains a constant frequency. The wind
begins to blow to the right, applying a constant horizontal
force F
S
on the hanging object. What is the magnitude of
the force the wind must apply to the hanging object so that
the string vibrates in its first harmonic as shown in Figure
18.73b?

Adiver named jacques observes a bubble of air rising from the bottom of a lake (where the absolute pressure is 3.50 atm) to the surface (where the pressure is 1.00 atm). the temperature at the bottom is 4.00 ∘c, and the temperature at the surface is 23.0 ∘c. what is the ratio of the volume of the bubble as it reaches the surface (vs) to its volume at the bottom (vb)? if jaques were to hold his breath the air in his lungs would be kept at a constant temperature. would it be safe for jacques to hold his breath while ascending from the bottom of the lake to the surface?