exam guide 2

Max pushes against a brick wall with a force of 10 newtons for a time of 5 seconds. How much work does Max do on the wall? None.

A book rests on a table, and the table rests on the ground. Which of the following pairs of forces forms a force pair, or action-reaction pair, obeying Newton’s law of force pairs? The table pushing up on the book and the book pushing down on the table.

An auto moves at a steady 50 mph down a straight level road. Which of the following is the forward drive force on the auto? The forward push by the road on the tires.

As the moon circles Earth, the net force on it is Directed inward toward Earth.

What similarity did Isaac Newton perceive between a falling apple and the moon? Both have forces on them toward Earth’s center, and accelerations directed toward Earth’s center.

Under what condition can a force act on an object and yet do no work on that object? If the object does not move.

How much work do you do when you lift a 3 N apple by 2 m during a time of 6 s? 6 J.

Samuel and Samantha are twins, born at the same time on Earth. Samantha is taken on a long trip into outer space, at a speed close to lightspeed, and returns to Earth. When she returns: Samuel and Samantha both observe that Samuel is older than Samantha.

According to Einstein’s general theory of relativity, the apparent gravitational “force” exerted by one object on another actually results from: The warping of space-time created by the first object, which then modifies the trajectory of the second object.

Which one of the following is responsible for the “one-way” nature of time, i.e. for the distinction between past and future? The second law of thermodynamics.

The three main types of radiation produced by the sun are: Infra-red, visible, and ultra-violet.

The “efficiency” of a heat engine is defined to be: Work output divided by thermal energy input.

All magnetic forces are produced by: Charges in motion.

According to the principle of equivalence, gravity is equivalent to: Acceleration.

Different colors correspond to electromagnetic waves of different: Frequencies.

Christian sends a laser beam toward Sonja. As the tip of the beam passes her rocket, Sonja observes that: The laser beam moves past her at 300,000 km/s.

Since matter is made of electrically charged particles, why don’t we feel electric forces all the time? Because ordinary matter contains as many electrons as protons, leading to no net macroscopic effect.

How does a radio station transmit a radio signal to your ear? Electrons moving in the station’s antenna send out an electromagnetic wave that travels to your radio, where the wave is transformed into a sound wave that travels to your ear.

When you touch a piece of ice: Thermal energy flows from your hand to the ice.

Ernest Rutherford’s experiments demonstrated that: The atom contains a tiny nucleus containing most of the atom’s mass.

A current flowing through a wire gives rise to: A magnetic field circulating around the wire.

You are in a spaceship moving past Earth at nearly lightspeed. You observe Mort on Earth. You measure his mass, pulse rate, and size. They are different because: Mass has increased, pulse rate has slowed down, and size is reduced along the direction of motion.

When light passes through a double slit and falls on a screen: Constructive interference occurs where the crests of one wave arrive with the crests of the other.

In the Electric Motor mini-lab, the role of the magnet is: Its magnetic field applies a sideways force to the wire only when a current is flowing in the wire.

The relationship E = mc^2 applies to: All forms of energy.

The approximate 14C content of the remains of a saber-toothed-tiger 24,000 years later would be: 1/16 gram.

Which of the following is not a heat engine? Hydro-electric generating plant.

Explain why, in terms of photons, ultraviolet light can damage cells in your skin but visible light cannot: Ultraviolet photons have more energy.

The naturally-occurring isotope that will sustain a fission chain reaction is: 235U

Which one has the shortest wavelength, assuming that they all have the same speed? Electron.