物理碗全题库

On February 20, 2008, there was a total lunar eclipse. What was the phase of the Moon during the eclipse?

In which Region(s) is there a place on the x-axis (aside from infinity) at which the electric potential is equal to zero?（含图）

In which Region(s) is there a place on the x-axis (aside from infinity) at which the electric field is equal to zero?（含图）

Astronauts on the Moon perform an experiment with a simple pendulum that is released from the horizontal position at rest. At the moment shown in the diagram with（含图）, the total acceleration of the mass may be directed in which of the following ways?

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An electron moves in the plane of the page through two regions of space along the dotted-line trajectory shown in the figure. There is a uniform electric field in Region I directed into the plane of the page (as shown). There is no electric field in Region II. What is a necessary direction of the magnetic field in regions I and II? Ignore gravitational forces. 

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A uniform meter stick has a 45.0 g mass placed at the 20cm mark as shown in the figure. If a pivot is placed at the 42.5cm mark and the meter stick remains horizontal in static equilibrium, what is the mass of the meter stick? 

（含图）

（含图）

An ideal gas is enclosed in a container. The volume of the container is reduced to half the original volume at constant temperature. According to kinetic theory, what is the best explanation for the increase in pressure created by the gas?

（含图）

（含图）

（含图）

A parallel-plate capacitor is connected to a battery. Without disconnecting the capacitor, a student pulls the capacitor’s plates apart so that the plate separation doubles. As a result of this action, what happens to the voltage across the capacitor and the energy stored by the capacitor?

Electron #1 moves with speed 0.30c where c is the speed of light. Electron #2 moves with speed 0.60c . What is the ratio of the kinetic energy of electron #2 to electron #1?

A traveling wave has the form y(x,t) = 3.0sin(2.5 x − 5.0t) where all quantities given are in MKS units, x is position, and t represents time. What is the period of the wave (in seconds)?

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（含图）

A circuit consists of a resistor, capacitor, and inductor connected in series to an AC source. As the source frequency increases, the current in the circuit decreases. Which statement about the circuit is NOT correct as the source frequency increases? 

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（含图）

Approximately how many seconds is it until the PhysicsBowl takes place in the year 2109 ?