In lab you find that a 1 -kg rock suspended above water weighs $10 \mathrm{~N}$. When the rock is suspended beneath the surface of the water, the scale reads $8 \mathrm{~N}$.

What physics principle underlies these three observations? When passing an oncoming truck on the highway, your car tends to sway toward the truck. The canvas roof of a convertible car bulges upward when the car is traveling at high speeds. The windows of older trains sometimes break when a high-speed train passes by on the next track.

What physics principle underlies the following three observations? When passing an oncoming truck on the highway, your car tends to sway toward the truck. The canvas roof of a convertible car bulges upward when the car is traveling at high speeds. The windows of older passenger trains sometimes break when a high-speed train passes by on the next track.

The wings of a certain airplane have a total bottom surface area of 100 m2. At a particular speed, the difference in air pressure below and above the wings is 4% of atmospheric pressure. Show that the lift on the airplane is $4 \times 105$ N.

If a certain spring stretches 4 cm when a load of 10 N is suspended from it, how much will the spring stretch if it is cut in half and $10 \mathrm{~N}$ is suspended from it?

Calculate the water pressure at the base of Hoover Dam. The depth of water behind the dam is 220 m. (Neglect the pressure due to the atmosphere.)

Calculate the pressure a $10 \mathrm{~N}$ block exerts on the table it rests on if its area of contact is $50 \mathrm{~cm}^2$.

Pressure $=$ weight density $\times$ depth

(Use $10,000 \mathrm{~N} / \mathrm{m}^3$ for the weight density of water, and ignore the pressure due to the atmosphere in the calculations below.)

The top floor of a building is 50 m above the basement. Calculate how much greater the water pressure is in the basement compared with the pressure on the top floor.

Consider these three animals: A. dog, B. horse, and C. elephant. Rank them, from highest to lowest, for their a. surface areas. b. masses. c. weights. d. volumes. e. surface area per weight.

Suppose that you balance a 5-kg ball on the tip of your finger, which has an area of $1 {cm^2$. Show that the pressure on your finger is$49 {N} / {cm}^2$, which is$490 {kPa}$.

Suppose that you are given the choice between two life preservers that are identical in size, the first a light one filled with Styrofoam and the second, a very heavy one, filled with gravel. If you submerge these life preservers in the water, upon which will the buoyant force be greater? Upon which will the buoyant force be ineffective? Explain why answers differ.

Should the "flat" ends of a very large wooden barrel for storing wine be concave (bending inward) or convex (bending outward)? Why?

Suppose you are given rhe choice between two life preservers that are identical in size, the first a light one filled wirh Styrofoam and rhe second a very heavy one filled wirh lead pellets. If you submerge these life preservers in the water, upon which is the buoyant force greater? Upon which is the buoyant force ineffective? Why are your answers different?

Suppose that you are given the choice between two life preservers that are identical in size, the first a light one filled with Styrofoam and the second a very heavy one filled with gravel. If you submerge these life preservers in the water, upon which will the buoyant force be greater? Upon which will the buoyant force be ineffective? Why are your answers different?