Question 1

Why is it fundamentally impossible to resolve individual atoms using a standard optical microscope?

Accepted Answer

Because the wavelength of visible light is much larger than the size of an atom, causing diffraction to blur the image.

Question 2

A 1-mm cube is scaled up by a factor of 5 in all dimensions. What is its new surface area?

Accepted Answer

$$150\ \mathrm{mm}^2$$

Question 3

A spring has an unextended length of $$1\ \mathrm{m}. $$When a $$200\ \mathrm{N}$$ weight is hung from it, it extends by $$10\ \mathrm{cm}. If a$$ $$400\ \mathrm{N}$$ weight is hung from it, what is the new length of the spring?

Accepted Answer

$$1.2\ \mathrm{m}$$

Question 4

A block has a mass of $$600\ \mathrm{g}$$ and a density of $$3000\ \mathrm{kg/m}^3. $$What is its volume?

Accepted Answer

$$200\ \mathrm{cm}^3$$

Question 5

A ping-pong ball bobs up and down 6 complete cycles in 3 seconds as a wave of wavelength $$5\ \mathrm{m}$$ passes by. What is the speed of the wave?

Accepted Answer

$$10\ \mathrm{m/s}$$

Question 6

A dam is constructed to be much thicker at the bottom than at the top. What is the main physical reason for this design?

Accepted Answer

Water pressure increases with depth, so the bottom must withstand greater pressure.

Question 7

A balloon expands to four times its original volume. What happens to its density?

Accepted Answer

It reduces by a factor of 4.

Question 8

A heat engine absorbs $$500\ \mathrm{J} of $$heat and does $$200\ \mathrm{J} of $$mechanical work. What is the change in internal energy of the system?

Accepted Answer

$$300\ \mathrm{J}$$

Question 9

Which of the following best describes an adiabatic system?

Accepted Answer

A system that has no exchange of heat.

Question 10

To maximize the efficiency of a heat engine, you should:

Accepted Answer

Increase the temperature difference between the hot reservoir and the cold sink.

Question 11

Which of the following is true about the buoyant force on a floating object?

Accepted Answer

It is equal to both the object's weight and the weight of the liquid displaced.

Question 12

A fog is different from a cloud primarily because of its:

Accepted Answer

Altitude.

Question 13

Which of the following best explains why glass is a good electrical insulator?

Accepted Answer

Its outer electrons are tightly bound to glass atoms.

Question 14

Which process requires a medium to transfer heat?

Accepted Answer

Both conduction and convection.

Question 15

A blue shift in the light from a distant star indicates that the star is:

Accepted Answer

Moving toward you.

Question 16

Which of the following is a property shared by all types of waves?

Accepted Answer

Interference.

Question 17

When a load is placed on the middle of a horizontal beam supported at each end, the top part of the beam undergoes:

Accepted Answer

Compression.

Question 18

Which of the following best explains why evaporation is a cooling process?

Accepted Answer

Highly energetic molecules escape from the liquid surface, removing energy.

Question 19

A vacuum in a thermos flask is effective because it eliminates:

Accepted Answer

Convection.

Question 20

Which of the following best describes the difference between a gas and a plasma?

Accepted Answer

A plasma has a sea of free electrons and can conduct current.

Step-by-Step Guidance for Physics Practice Exam #2

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