Physics Trivia Questions for Students — page 7

An electron (mass = m, charge = -E) is rotated with speed V upwards, in the plane of the page, into a region containing a uniform magnetic field B, that is directed into the plane of the page. Describe the electron's subsequent circular motion.

• AClockwise rotation; radius of path = eB/(mv)
• BCounterclockwise rotation; radius of path = eB/(mv)
• CClockwise rotation; radius of path = mv/(eB)
• DCounterclockwise rotation; radius of path = mv/(eB)

The charge on an oil drop is measured in the laboratory. Which of the following measurements should be rejected as highly unlikely to be correct?

• A8.0 × 10^-19 C
• B2.4 × 10^-19 C
• C4.8 × 10^-19 C
• D6.4 × 10^-19 C

A person stands on a scale in an elevator. He notices that the scale reading is less than his usual weight. Which of the following could possibly describe the motion of the elevator?

• AIt is moving downward at a constant speed.
• BIt is moving downward and slowing down.
• CIt is moving upward and slowing down.
• DIt is moving upward at a constant speed.

The nucleus of an electrically neutral iron atom contains 26 protons. The number of electrons this iron atom has is

• A52
• B26
• C24
• DNone.

In which of the following situations involving a source of sound and a detector of the sound is it possible that there is NO perceived Doppler shift?

• AThe source travels toward the stationary detector.
• BBoth the source and detector travel in opposite directions, with the source and detector moving away from each other.
• CThe detector travels toward the stationary source.
• DBoth the source and detector travel in the same direction.

A string of fixed tension and linear mass density is attached to a vibrating speaker. It is observed that a speaker frequency of 60 Hz does not produce standing waves in the string. Which explanation for this phenomenon is correct?

• AThe wave speed on the string is fixed.
• BThe wavelength of the wave produced by the speaker is equal to the speed of waves on the string divided by 60 Hz.
• CThe string length is not a multiple of half the wavelength of the wave.
• D60 Hz is in the lowest range of audible sound.

A karate chop delivers a force of 3000 N to a board that breaks. The force that the board exerts on the hand during this event is

• Agreater than 3000 N
• BNeed more information
• Cless than 3000 N
• D3000 N

A proton enters a solenoid. Upon entry, the proton is moving in a straight line along the axis of the solenoid. Which of the following is a correct description of the proton's motion within the solenoid?

• AThe proton will continue in its straight path and slow down.
• BThe proton will be bent in a circular path.
• CThe proton will continue in its straight path at constant velocity.
• DThe proton will be bent in a parabolic path.

To view your full-face image in a steamy mirror compared with the height of your face the minimum height of the patch to wipe away is

• Athe same.
• Bone-half.
• Cdependent on your distance from the mirror.
• Done-quarter.

An object is placed 10 cm in front of a diverging mirror. What is the focal length of the mirror if the image appears 2 cm behind the mirror?

• A-2/5 cm
• B-5/3 cm
• C-5/2 cm
• D-3/5 cm

The red glow in the neon tube of an advertising sign is a result of

• Apolarization.
• Bfluorescence.
• Ccoherence.
• Dde-excitation.

An object is placed 100 cm from a plane mirror. How far is the image from the object?

• A50 cm
• B100 cm
• C200 cm
• D300 cm

Which of the following correctly describes the motion of a real object in free fall? Assume that the object experiences drag force proportional to speed and that it strikes the ground before reaching terminal sped.

• AIt will fall with increasing speed and increasing acceleration.
• BIt will fall with decreasing speed and decreasing acceleration.
• CIt will fall with increasing speed and decreasing acceleration.
• DIt will fall with decreasing speed and increasing acceleration.

The highest ocean tides occur when Earth and the Moon are

• Alined up during spring
• Bat any angle to the Sun
• Cat right angles to the Sun
• Dlined up with the Sun

A stone is thrown vertically upward with an initial speed of 5 m/s. What is the velocity of the stone 3 seconds later?

• A25 m/s, upward
• B25 m/s, downward
• C35 m/s, downward
• D35 m/s, upward

When an element ejects a beta particle, the atomic number of that element

• Areduces by 1
• Bincreases by 1
• Creduces by 2
• Dincreases by 2

Light reflecting from a smooth surface undergoes a change in

• Afrequency.
• Bwavelength.
• CNone of these.
• DAll of these.

Two objects, A and B, have equal charge and equal mass. Neither body is in motion because the gravitational and electrostatic forces between them are equal. If the mass of Object A is halved, equilibrium will be maintained if

• Athe charge on Object B were doubled
• Bthe charge on Object A were doubled
• Cthe charge on Object B were halved
• Dthe mass on Object B were halved

Which of the following statements about images is true?

• AImages produced by concave mirros are always real.
• BImages produced by convex mirrors can be both real and virtual.
• CImages produced by concave lenses are always real.
• DImages produced by convex lenses can be both real and virtual.

As more lamps are connected in parallel in a circuit, the current in the power source

• Aincreases
• Bremains the same
• CNot enough information to say
• Ddecreases

A bi-convex lens has a radius of curvature of magnitude 20 cm. Which of the following best describes the image formed of an object of height 2 cm placed 30 cm from the lens?

• AVirtual, inverted, height = 0.25 cm
• BReal, inverted, height = 1 cm
• CReal, upright, height = 1 cm
• DVirtual, upright, height = 0.25 cm

An object of mass 2 kg is acted upon by three external forces, each of magnitude 4 N. Which of the following could NOT be the resulting acceleration of the object?

• A0 m/s^2
• B8 m/s^2
• C4 m/s^2
• D2 m/s^2

If L, M, and T denote the dimensions of length, mass, and time, respectively, what are the dimensions of impulse?

• ALM/T^3
• BLM/T
• CLM/T^2
• DL^2M/T^2

A sphere starts from rest atop a hill with a constant angle of inclination and is allowed to roll without slipping down the hill. What force provides the torque that causes the sphere to rotate?

• AKinetic friction
• BGravity
• CStatic friction
• DThe normal force of the hill on the sphere

Newton's law of cooling applies to objects that

• Awarm up
• BNeither
• Ccool
• DBoth

An object is released from rest and falls a distance h during the first second of time. How far will it fall during the next second of time?

• A3h
• B2h
• Ch
• D4h

When you breathe on your hand, the temperature of the exhaled air reaching your hand

• Adepends on how you blow
• Bdecreases
• Cremains unchanged
• Dincreases

To say that a rose petal is red is to say that it

• Aemits red
• Btransmits red
• Creflects red
• Dabsorbs red

An alarm whose frequency is 400 Hz is dropped out of a third-floor window. The student who drops it measures the frequency with a very sensitive oscilloscope. The measured frequency

• Aappears lower than 400 Hz and the frequency decreases as it falls
• Bappears higher than 400 Hz and the frequency increase as it falls
• Cappears higher than 400 Hz and the frequency decreases as it falls
• Dappears lower than 400 Hz and the frequency increases as it falls

Atmospheric pressure is due to the weight

• Aof planet Earth itself
• Band volume of the atmosphere
• Cof the atmosphere
• Ddensity and volume of the atmosphere

A diffraction grating relies on light

• Avariations in brightness
• Binterference
• Cbeing composed of photons
• Damplitudes

When you scale up an object to 3 times its linear size, the surface area increases by

• A4 and the volume by 8.
• B3 and the volume by 9.
• C9 and the volume by 27.
• D3 and the volume by 27.

How much work is required to charge a 10 µF capacitor to a potential difference of 100 V ?

• A0.1 J
• B0.01 J
• C0.05 J
• D0.005 J

A rock is dropped off a cliff and strikes the ground with an impact velocity of 30 m/s. How high was the cliff?

• A45 m
• B20 m
• C60 m
• D30 m

The greenish-blue color of ocean water is due mostly to light that hasn't been

• Aabsorbed
• Bscattered
• Creflected
• Drefracted

The factors, both of which will increase the magnetic field strength of an electromagnet, are

• Ausing an air core instead of iron and increasing the diameter of the coil
• Bincreased electrical current and fewer coils of wire
• Can increase in the electrical current and using a strong ferromagnetic material like iron
• Dincreased diameter of coil and an increase in the number of coils

The weight of a box on the Earth is 80 N. What is the weight of the box on the moon if the moon has 1/80th the mass and 1/4th the radius of the Earth?

• A10 N
• B20 N
• C1 N
• D16 N

The metal detectors people walk through at airports operate via

• AOhm's law
• BCoulomb's law
• CNewton's laws
• DFaraday's law

To receive an electric shock there must be a

• Acurrent in one direction.
• Bhigh voltage and low body resistance.
• Cvoltage difference across part or all of your body.
• Dpresence of moisture.

Electricity and magnetism connect to form

• Aultrahigh-frequency sound
• Blight
• Cmass
• Denergy

The rotational inertia of an object is greater when most of the mass is located

• Aoff center
• Bon the rotational axis
• Cnear the rotational axis
• Daway from the axis

Chain reactions in a fission reactor are caused by

• Akinetic energy
• Bejected neutrons
• Cenergy conversion
• Dmass conversion

The phenomenon of beats is the result of sound

• Aamplification
• Bresonance
• Cinterference
• Ddestruction

According to Hooke's law, if you hang by a tree branch and note how much it bends, then hanging with twice the weight produces

• Athe same bend if the branch doesn't break.
• Btwice the bend.
• Chalf the bend.
• D4 times the bend.

If two non-zero vectors are added together, and the resultant vector is zero, what must be true of the two vectors?

• AIt is not possible for the sum of two non-zero vectors to be zero.
• BThey have equal magnitude and are pointed in opposite directions.
• CThey have equal magnitude and are pointed in the same direction.
• DThey have different magnitudes and are pointed in opposite directions.

Astrophysicists are able to identify the elements in the outer layers of a star by studying its

• Aspectrum.
• BDoppler effect.
• Ctemperature.
• Dmolecular structure.

When 100 J are put into a device that puts out 40 J of useful work, the efficiency of the device is

• A140%
• B60%
• C40%
• D50%

A microwave oven is connected to an outlet, 120 V, and draws a current of 2 amps. At what rate is energy being used by the microwave oven?

• A30 W
• B60 W
• C10 W
• D240 W

Sound will travel fastest in

• Aocean water
• Ba wooden plank
• Ca steel beam
• Dair in a balloon

When the temperature of a strip of iron is increased, the length of the strip

• Amay increase and may decrease.
• Bdecreases in width as it gets longer.
• Cactually decreases.
• Dalso increases.