Official Physics GRE Exam #5
Question & Answers 2026
A rock is thrown vertically upward with initial speed v0.
Assume a friction force proportional to -v, where v is the
velocity of the rock, and neglect the buoyant force
exerted by air. Which of the following is correct?
(A) The acceleration of the rock is always equal to g.
(B) The acceleration of the rock is equal to g only at the
top of the flight.
(C) The acceleration of the rock is always less than g.
(D) The speed of the rock upon return to its starting point
is v0.
(E) The rock can attain a terminal speed greater than v0
before it returns to its starting point. - CORRECT
ANSWERS ✔✔The acceleration of the rock should only
be constant at the top due to an instantaneous point of
rest at the top of that flight. Choice (B).
A satellite orbits the Earth in a circular orbit. An astronaut
on board perturbs the orbit slightly by briefly firing a
control jet aimed toward the Earth's center. Afterward,
which of the following is true of the satellite's path?
(A) Ellipse (B) Hyperbola (C) Circle with larger radius. (D)
Spiral with increasing radius (E) Many radial oscillations
per revolution. - CORRECT ANSWERS ✔✔We get a
tendency toward an orbit for the object and hence
become elliptical. Choice (A).
, Official Physics GRE Exam #5
Question & Answers 2026
For blue light, a transparent material has a relative
permittivity (dielectric constant) of 2.1 and a relative
permeability of 1.0. If the speed of light in a vacuum is c,
the phase velocity of blue light in an unbounded medium
of this material is - CORRECT ANSWERS ✔✔c/sqrt(2.1),
which is given by the ratio of the dielectric constants
which is 2.1/1.0 and that gives us: c/sqrt(2.1). Choice (D).
The equation y = Asin(2*pi*(t/T - x/lambda), where A, T,
and lambda are positive constants, represents a wave
whose
(A) amplitude is 2A
(B) velocity is in the negative x-direction
(C) period is T/lambda
(D) speed is x/t
(E) speed is lambda/T - CORRECT ANSWERS ✔✔The
speed is lambda/T, which is given by the equation and
representative of the units. Choice (E).
Two small spheres of putty, A and B, of mass M and 3M,
respectively, hang from the ceiling on strings of equal
length l. Sphere A is drawn aside so that it is raised to a
height h0 as shown above and then released. Sphere A
Question & Answers 2026
A rock is thrown vertically upward with initial speed v0.
Assume a friction force proportional to -v, where v is the
velocity of the rock, and neglect the buoyant force
exerted by air. Which of the following is correct?
(A) The acceleration of the rock is always equal to g.
(B) The acceleration of the rock is equal to g only at the
top of the flight.
(C) The acceleration of the rock is always less than g.
(D) The speed of the rock upon return to its starting point
is v0.
(E) The rock can attain a terminal speed greater than v0
before it returns to its starting point. - CORRECT
ANSWERS ✔✔The acceleration of the rock should only
be constant at the top due to an instantaneous point of
rest at the top of that flight. Choice (B).
A satellite orbits the Earth in a circular orbit. An astronaut
on board perturbs the orbit slightly by briefly firing a
control jet aimed toward the Earth's center. Afterward,
which of the following is true of the satellite's path?
(A) Ellipse (B) Hyperbola (C) Circle with larger radius. (D)
Spiral with increasing radius (E) Many radial oscillations
per revolution. - CORRECT ANSWERS ✔✔We get a
tendency toward an orbit for the object and hence
become elliptical. Choice (A).
, Official Physics GRE Exam #5
Question & Answers 2026
For blue light, a transparent material has a relative
permittivity (dielectric constant) of 2.1 and a relative
permeability of 1.0. If the speed of light in a vacuum is c,
the phase velocity of blue light in an unbounded medium
of this material is - CORRECT ANSWERS ✔✔c/sqrt(2.1),
which is given by the ratio of the dielectric constants
which is 2.1/1.0 and that gives us: c/sqrt(2.1). Choice (D).
The equation y = Asin(2*pi*(t/T - x/lambda), where A, T,
and lambda are positive constants, represents a wave
whose
(A) amplitude is 2A
(B) velocity is in the negative x-direction
(C) period is T/lambda
(D) speed is x/t
(E) speed is lambda/T - CORRECT ANSWERS ✔✔The
speed is lambda/T, which is given by the equation and
representative of the units. Choice (E).
Two small spheres of putty, A and B, of mass M and 3M,
respectively, hang from the ceiling on strings of equal
length l. Sphere A is drawn aside so that it is raised to a
height h0 as shown above and then released. Sphere A
