Physics Answers

9. A sealed tank containing seawater to a height of 11.0 m also contains air above the water at a gauge pressure of 3.00 atm. Water flows out from the bottom through a small hole. How fast is this water moving?

7. Water runs into a fountain, filling all the pipes, at a steady rate of 0.750 m³/s. (a) How fast will it shoot out of a hole 4.50 cm in diameter? (b) At what speed will it shoot out if the

diameter of the hole is three times as large?

5. A Ping-Pong ball has a diameter of 3.80 cm and average density

of 0.084 0 g/cm3. What force is required to hold it completely

submerged under water?

4. A frog in a hemispherical pod, as shown in the figure on the right, just floats without sinking into a sea of blue-green ooze with density 1,35 g/cm3. If the pod has radius 6.00 cm and negligible mass, what is the mass of the frog?

2. A barrel contains a 0.120 m layer of oil floating on water that is 0.250 m deep. The density of the oil is 600 kg/m³. What is the gauge pressure at the oil- water interface and at the bottom of the barrel?

1. A 60 kg woman walking through an alley accidentally broke the heel of her left high-heeled

shoes. Now the woman tries to balance on one heel of a pair of high-heeled shoes. If the heel is circular and has a radius of 0.500 cm, what pressure does she exert on the floor?

10. A 2.50-kg rock is attached at the end of a thin, very light rope 1.45 m long. You start it

swinging by releasing it when the rope makes an 11° angle with the vertical. You record the observation that it rises only to an angle of 4.5° with the vertical after swings. (a) How much energy has this system lost during that time? (b) What happened to the "lost" energy? Explain how it could have been "lost."

7. In a physics lab, you attach a 0.200-kg air-track glider to the end of an ideal spring of

negligible mass and start it oscillating. The elapsed time from when the glider first moves

through the equilibrium point to the second time it moves through that point is 2.60 s.

Find the spring's force constant.

6. A machine part is undergoing SHM with a frequency of 5.00 Hz and amplitude 1.80 cm.

How long does it take the part to go from x=0 to x=-1.80 cm.

5. In a materials testing laboratory, a metal wire made from a new alloy is found to break when a tensile force of 90.8 N is applied perpendicular to each end. If the diameter of the wire is 1.84 mm, what is the breaking stress of the alloy?