Lesson 4 Flashcards
Which of the following is an example in which you are traveling at constant speed but not at constant velocity?
driving around in a circle at exactly 100 km/hr
Momentum is defined as
mass times velocity
As long as an object is not gaining or losing mass, a net force on the object will cause a change in
velocity
You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude?
The elevator is accelerating downwards.
The movement of a pool ball, after being struck by a cue, is an example of
Newton’s second law of motion.
Changing the orbit of a spacecraft by firing thrusters is an example of
Newton’s third law of motion.
What quantities does angular momentum depend upon?
mass, velocity, and radius
Which of the following is not a unit of energy?
kilowatt
Radiative energy is
energy carried by light.
What does temperature measure?
the average kinetic energy of particles in a substance
The amount of gravitational potential energy released as an object falls depends on
its mass and the distance it falls
According to the universal law of gravitation, the force due to gravity is
inversely proportional to the square of the distance between objects.
According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them will
decrease by a factor of 9.
The orbital period of a geosynchronous satellite is
23 hours 56 minutes.
According to what we now know from Newton’s laws, which of the following best explains why Kepler’s second law is true?
A planet’s angular momentum must be conserved as it moves around its orbit.
Suppose a lone asteroid happens to be passing relatively near Jupiter (but not near any of its moons), following a hyperbolic orbit as it approaches Jupiter. Which of the following statements would be true?
The asteroid’s orbit around Jupiter would not change, and it would go out on the same hyperbolic orbit that it came in on.
Imagine we’ve discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet?
It is less massive than Earth.
The energy attributed to an object by virtue of its motion is known as
kinetic energy.
Which of the following best explains why the Moon’s orbital period and rotation period are the same?
The Moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period.
