Question 1

A satellite is moved from a circular orbit of radius $$R to a $$new circular orbit of radius $$2R$$ around Earth. Which of the following statements correctly describes the change in the satellite's kinetic energy?

Accepted Answer

The kinetic energy decreases by a factor of $$\frac{1}{\sqrt{2}}.$$

Question 2

Which of the following best explains why the gravitational potential energy $$U$$ between two masses is negative?

Accepted Answer

Because zero potential energy is defined at infinity, and bound systems require energy input to separate.

Question 3

A comet in an elliptical orbit around the Sun moves fastest when it is closest to the Sun. Which principle explains this behavior?

Accepted Answer

The potential energy is lowest at closest approach, so kinetic energy is highest to keep total energy constant.

Question 4

Why do isotopes of the same element generally have the same chemical properties?

Accepted Answer

Because they have the same electron configuration, and chemistry depends on electrons.

Question 5

A steel ship floats in water while a solid steel block of the same mass sinks. What is the primary reason for this difference?

Accepted Answer

The ship is hollow, so its average density is less than water.

Question 6

Which of the following statements about hydrostatic pressure in a fluid is correct?

Accepted Answer

Pressure at a given depth depends only on the fluid's density and depth.

Question 7

A block of wood and a block of metal, both at room temperature, are touched. The metal feels colder. Why?

Accepted Answer

The metal conducts heat away from your hand faster than the wood.

Question 8

Which equation correctly expresses the energy stored in a stretched spring obeying Hooke's Law?

Accepted Answer

$$U = \frac{1}{2}kx^2$

Question 9

A diver is submerged in a lake. What determines the buoyant force acting on the diver?

Accepted Answer

The volume of water displaced by the diver.

Question 10

A gas is compressed at constant temperature so that its pressure doubles. According to Boyle's Law, what happens to its volume?

Accepted Answer

The volume halves.

Question 11

Why does sweating cool the human body so efficiently?

Accepted Answer

Because evaporation removes large amounts of energy due to water's high latent heat of vaporization.

Question 12

During a phase change, such as melting or boiling, what happens to the temperature of a substance as energy is added?

Accepted Answer

The temperature remains constant while energy changes the potential energy (bonding).

Question 13

Which of the following best describes the greenhouse effect from a physics perspective?

Accepted Answer

Shortwave radiation is absorbed and re-emitted as longwave radiation, which is trapped, raising equilibrium temperature.

Question 14

A patient receives a cold compress. Which mechanism of heat transfer is primarily responsible for the cooling effect?

Accepted Answer

Conduction

Question 15

Which of the following is a direct consequence of the inverse-square law for gravity?

Accepted Answer

The gravitational field strength decreases as $$1/r^2$$ because the field spreads over the surface area of a sphere.

Question 16

A hot object cools down in a room. According to Newton's Law of Cooling, how does the rate of cooling change over time?

Accepted Answer

It decreases exponentially as the temperature difference decreases.

Question 17

Why does climate tend to be more moderate near large bodies of water?

Accepted Answer

Because water has a high specific heat, so it absorbs and releases heat slowly.

Question 18

Which of the following best explains why ice floats on water, even though both are made of H$$_2O $$molecules?

Accepted Answer

Ice has a lower density due to its open lattice structure.

Question 19

A satellite in orbit has a total mechanical energy $$E = -\frac{GMm}{2r}. $$What does this negative value indicate?

Accepted Answer

The satellite is in a bound orbit and energy must be added for it to escape.

Question 20

A person climbs a mountain where the air pressure is lower than at sea level. What is the main reason for this decrease in pressure?

Accepted Answer

There is less air above, so the weight of the air column (and thus pressure) is less.

Physics Master Study Guide: Chapters 9–17 (Gravity, Orbits, Matter, Fluids, Gases, Heat, and Phase Changes)

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