HOMEWORK 5 - TEST BANK QUESTIONS

Water weighs about 10 N per liter on Earth. A 4.0 liter ball is pushed underwater on the space shuttle, where gravity was 1/10 that on Earth. What is the buoyant force on the ball?

4 N

Water weighs about 10 N per liter. A 4.0 liter ball is pushed underwater. What is the buoyant force on the ball?

40 N

The brake system in most cars makes use of a hydraulic system. This system consists of a fluid filled tube connected at each end to a piston. Assume that the piston attached to the brake pedal has a cross Section: al area of one half a square inch and the piston attached to the brake pad has a cross Section: area of two square inches. When you apply a force of 10 pounds to the piston attached to the brake pedal, the force at the brake pad will be

40 pounds

You are in a hot air balloon and are hovering in the air so that the atmospheric pressure remains constant. At a temperature of 300 K your balloon holds 5x106 liter of air. The sun comes out and the temperature rises to 330 K. What is the new volume of the balloon? You may assume that no air can exit or enter the balloon.

5.5 × 106 liter

Why will a rolled - up ball of aluminum foil float in water but solid aluminum will sink?

Due to the air inside, the average density of the ball is lower than water.

A popular drink is composed by pouring several types of beverage (one on top of the other) in order to get a layering effect. In what order should the individual beverages be poured into the glass so that your drink is stable?

Most dense first and then in order of decreasing density.

Gravity creates

Pressure gradients in fluids

Suppose you are ill and have to go to the hospital for shot. When the nurse points the fluid - filled syringe skyward to clear the air out of it, he presses the plunger down but no fluid comes out because the needle is plugged. When the plunger is pressed down and no fluid is moving,

The pressure of the fluid in the needle and much larger syringe are the same.

For an object that sinks in a fluid,

The weight of fluid displaced is less than its weight.

For an object that is neutrally buoyant in a fluid,

The weight of the fluid displaced equals the object's weight.

Cities have to use water towers to supply water to because

Water pressure at the bottom of the tower is much higher than at the top.

Why are failures in dams more likely to occur closer to the bottom of the dam?

Water pressure is higher at the bottom

For your high school science project you are able to get community support and terraform Mars, so that liquid water could exist on its surface. Suppose you have two cans of soda - one barely floats and one barely sinks in fresh water on Earth. Taking them to Mars, with the gravitational acceleration being 1/3 its value on earth,

We can't say anything until we know if the water on Mars is freshwater or not.

Suppose you had a very long straw that could reach from a cup of water on the ground level to the top of a very tall building. When you suck on the straw in order to bring water up,

You could bring the water up to only a certain height in the straw because the atmosphere pushes down on the surface of the water by a given amount.

You are floating along in a hot air balloon. You look up and notice that the bottom of the balloon is open. Neglecting any diffusion of molecules, hot air remains inside the balloon despite this opening because

convection naturally would make hot air rise, so it has no opening through which to escape.

A block of hardwood is floating easily on the surface of a lake. As a storm approaches, the density and pressure of the air above the lake begin to decrease. As a result of this decrease in air pressure and density, the block of wood

moves downward slightly and floats lower in the water.

You are trying to deliver water to a sink in the tree house in your backyard. You run an old hose from the spigot behind your home, across your yard, and up the tree to a sink inside the tree house. You let water fill the hose all the way to the tree house sink and then leave the hose pressurized overnight, with no water flowing in it. Unfortunately, the hose cannot tolerate high pressure anymore and it springs a leak around midnight. By morning your whole backyard is a swamp. The most likely site for the leak is

on the ground—the lowest point on the hose.

When driving down a level smooth road, your car tires flatten at the bottom and they nicely support the weight of your car. However when you run over a small pointed rock the tire is punctured and fails. The rock is able to puncture the tire because

the small surface area of the rock times the pressure in the tire is not enough force to support the car. Thus, the tire fails