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A crate weighing 6400 N has dimensions 1 m by 2 m by 4 m. On what side should this crate be placed on a surface so that it exerts the least pressure on that surface?
the side that is 1 by 2
Why do the roofs of homes often get blown off in a tornado?
The high speed wind blowing over a roof lowers the air pressure. The air under the roof is at normal pressure, and the higher pressure on the inside can lift the roof off of the walls of the house.
Why is it easier to unscrew a jar lid when it is placed under a stream of hot water?
The metal expands with the water
If the period of a pendulum is 4 s, what is its frequency?
.25 Hz
Under what conditions is water a conductor of electricity?
when there are salts in it
An object weighing 60 N having a volume of 5.9 liters is placed in water. What will happen?
it will sink
On which temperature scale is 0 degrees the lowest possible temperature?
The Kelvin scale
Is the elimination of all greenhouse gases a good idea and why or why not?
No because we need some to maintain a safe temperature
The period of a pendulum that has a length L = 1 m is 5 s. What would the period of this pendulum be if L = 4 m?
10 Seconds
Why is an uncharged conducting sphere attracted to a charged rod?
An uncharged metal sphere has free electrons that can move around inside it. When a negative rod is brought near an uncharged metal sphere, the electrons in the sphere are pushed away from the side of the sphere closest the rod and move to the other side of the sphere. As a result, the side of the sphere closest to the rod contains an excess of positive charges which are attracted to the negative charges on the rod. Because the excess electrons that moved away from the rod are farther away from the rod, the repulsive force on them is smaller than the attractive force between the positive charges and the rod. If a positively charged rod is brought near the uncharged metal sphere, electrons in the sphere move closer to the rod and there is still an attractive force.
Why does ice float.
it is less dense than water
What is meant by the internal energy of a system?
The internal energy of a system is the sum of the kinetic energy of all the molecules in it
Why does the inside of a car parked outside on a summer day get very hot?
Sunlight enters the car through the windows and heats up the inside of the car. The hot surfaces inside the car radiate energy in the infrared which is trapped in the car since infrared radiation is blocked by the glass windows. This is the greenhouse effect.
What is the difference between a transverse and a longitudinal wave? Give an example of each.
In a transverse wave segments of the medium vibrate in a direction that is perpendicular to the direction of the wave. Example: a wave on a string. In a longitudinal wave segments of the medium vibrate back and forth along the same direction that the wave propagates. Example: a sound wave.
What characteristic of a tuning fork determines the frequency of the sound wave that it produces?
the length because if it is short it will produce a low pitch and vice versa
What is it necessary to maintain a pressure difference between the ends of a long pipe to keep water flowing through the pipe?
Water moves from low pressure to high pressure
What is 50 Fahrenheit in Celsius?
What factors affect the change in phase of a substance?
Heat and Pressure
A gas absorbs 500 J of heat energy while doing work. If the internal energy of the gas decreased by 1000 J in this process, how much work was performed by the gas?
1500 J
What are (a) the wavelength, and (b) frequency of a wave; and (c) how are they related?
(a) The wavelength of a wave is the spatial distance over which the wave is repeated. It is the distance between successive wavelengths. The frequency ( f ) of a wave is the number of wave cycles occurring each second. (c) Wavelength and frequency are related by the periodic wave relation.
What is viscosity?
the resistance to flow or how sticky something is
What are the three mechanisms of heat flow?
Convection, Conduction, and Radiation
State the first law of thermodynamics.
If an amount of heat Q is absorbed by a system and the system performs an amount of work W, the internal energy of the system changes by an amount U=Q-W.
Why are waves important?
Waves are important because they provide a mechanism for the transport of energy without the transport of matter.
If the speed of sound is 330 m/s, (a) what is the wavelength of the tuba’s A2 (110 Hz) tone, and (b) what is the wavelength of the piccolo’s A6 tone (1760 Hz)?
(a) 3 m (b).19 m