PHY 241 Test 2 Study Guide With
Complete Solutions
What are the three ways to accelerate? - ANSWER 1. Speeding up
2. Slowing down
3. Turning
What is the direction of acceleration with respect to velocity when acceleration
is speeding up? - ANSWER The acceleration is in the positive direction
The velocity is in the positive direction
What is the direction of acceleration with respect to velocity when acceleration
is slowing down? - ANSWER Acceleration is in the positive direction
Velocity is in the negative direction
What is the direction of acceleration with respect to velocity when acceleration
is turning - ANSWER Acceleration is towards the center of the circle
Velocity is moving straight forward
What is the meaning of centripetal? - ANSWER Towards the center
(of the turn)
What is the meaning of centrifugal? - ANSWER Away from the center
(of the turn)
What is the meaning of the words "uniform" and "circular" in the expression
"uniform circular motion"? - ANSWER Uniform - "at constant speed"
Circular - travelling on a circular path
Uniform circular motion - motion traveling at a constant speed on a circular path
What is the definition of period? - ANSWER The period, T, is the time required for
one compete revolution
T = 1/f
What is the definition of frequency? - ANSWER Frequency, f, is the number of
revolutions per second
f=1/T
What are the formulas for centripetal acceleration? - ANSWER v = 2πr/T = 2πrf =
rω
, a_c= v^2/r =(4π^2 r)/T^2 = 4π^2 f^2 r = ωv = rω^2
What is Newton's Law of Universal gravitation in words or in a formula? -
ANSWER Any two masses attract each other with a force that is proportional to
each of the masses and inversely proportional to the square of the distance
(center to center) between the objects.
F=G (m_1 m_2)/r^2
What is the statement of Kepler's first law of planetary moiton? - ANSWER The
path of each planet about the Sun is an ellipse with the Sun at one focus
Planets travel in elliptical orbits, with the sun at a focus
What is the meaning of Kepler's first law of planetary moiton? - ANSWER An
ellipse is a closed curve such that the sum of the distances from any point P on
the curve to two fixed points remain constant. Thus, the sum of the two
distances is the same for all points on the curve.
What is the statement of Kepler's second law of Planetary Motion? - ANSWER
Lines drawn from the sun to a planet sweep equal areas in equal times
Each planet moves so that an imaginary line drawn from the Sun to the planet
sweep out equal areas in equal periods of time
What is the meaning of Kepler's second law of Planetary Motion? - ANSWER
Planets go faster when closer and slower when farther from the sun
Planets do not travel at a constant speed; they travel fastest at perihelion and
slowest at aphelion
What is the statement of Kepler's third law of planetary motion? - ANSWER The
square of the period is proportional to the cube of distance from the sun
The ratio of the squares of the periods of any two planets revolving around the
Sun is equal to the ratio of the cubes of their semi major axes
What is the meaning of Kepler's third law of planetary motion? - ANSWER
Planets that are farther away from the sun take longer to complete their orbits
What was Galileo's first telescopic discovery, and how did it challenge the
beliefs generally held at the time? - ANSWER Galileo's first observation was the
phases of Venus
He found that Venus goes around the sun
This discovery challenged that the earth was the center of the universe.
By having a planet that revolved around something other than the Earth, it was
saying that the Earth was not the center of the universe.
Complete Solutions
What are the three ways to accelerate? - ANSWER 1. Speeding up
2. Slowing down
3. Turning
What is the direction of acceleration with respect to velocity when acceleration
is speeding up? - ANSWER The acceleration is in the positive direction
The velocity is in the positive direction
What is the direction of acceleration with respect to velocity when acceleration
is slowing down? - ANSWER Acceleration is in the positive direction
Velocity is in the negative direction
What is the direction of acceleration with respect to velocity when acceleration
is turning - ANSWER Acceleration is towards the center of the circle
Velocity is moving straight forward
What is the meaning of centripetal? - ANSWER Towards the center
(of the turn)
What is the meaning of centrifugal? - ANSWER Away from the center
(of the turn)
What is the meaning of the words "uniform" and "circular" in the expression
"uniform circular motion"? - ANSWER Uniform - "at constant speed"
Circular - travelling on a circular path
Uniform circular motion - motion traveling at a constant speed on a circular path
What is the definition of period? - ANSWER The period, T, is the time required for
one compete revolution
T = 1/f
What is the definition of frequency? - ANSWER Frequency, f, is the number of
revolutions per second
f=1/T
What are the formulas for centripetal acceleration? - ANSWER v = 2πr/T = 2πrf =
rω
, a_c= v^2/r =(4π^2 r)/T^2 = 4π^2 f^2 r = ωv = rω^2
What is Newton's Law of Universal gravitation in words or in a formula? -
ANSWER Any two masses attract each other with a force that is proportional to
each of the masses and inversely proportional to the square of the distance
(center to center) between the objects.
F=G (m_1 m_2)/r^2
What is the statement of Kepler's first law of planetary moiton? - ANSWER The
path of each planet about the Sun is an ellipse with the Sun at one focus
Planets travel in elliptical orbits, with the sun at a focus
What is the meaning of Kepler's first law of planetary moiton? - ANSWER An
ellipse is a closed curve such that the sum of the distances from any point P on
the curve to two fixed points remain constant. Thus, the sum of the two
distances is the same for all points on the curve.
What is the statement of Kepler's second law of Planetary Motion? - ANSWER
Lines drawn from the sun to a planet sweep equal areas in equal times
Each planet moves so that an imaginary line drawn from the Sun to the planet
sweep out equal areas in equal periods of time
What is the meaning of Kepler's second law of Planetary Motion? - ANSWER
Planets go faster when closer and slower when farther from the sun
Planets do not travel at a constant speed; they travel fastest at perihelion and
slowest at aphelion
What is the statement of Kepler's third law of planetary motion? - ANSWER The
square of the period is proportional to the cube of distance from the sun
The ratio of the squares of the periods of any two planets revolving around the
Sun is equal to the ratio of the cubes of their semi major axes
What is the meaning of Kepler's third law of planetary motion? - ANSWER
Planets that are farther away from the sun take longer to complete their orbits
What was Galileo's first telescopic discovery, and how did it challenge the
beliefs generally held at the time? - ANSWER Galileo's first observation was the
phases of Venus
He found that Venus goes around the sun
This discovery challenged that the earth was the center of the universe.
By having a planet that revolved around something other than the Earth, it was
saying that the Earth was not the center of the universe.
