Honors Physics Chapter 7

True or false: the net force on an object in orbit is zero

False

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same centripetal acceleration

False

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same linear displacement

False

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same tangential acceleration

False

True or false: when a rigid body rotates about a fixed axis all the points on the body have the same tangential speed

False

True or false: the constant K in Kepler's Third Law is the same for all the planets in our solar system, but different for planetary systems orbiting other stars

True

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same angular acceleration

True

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same angular displacement

True

True or false: when a rigid body rotates about a fixed axis all the points in the body have the same angular speed

True

True or false: Newton never knew the value of "his" universal gravitational constant G

True (I think the quotes give it away but that's what she wrote)

For a spherical planet to act like a "point mass" so that, externally, F=GmM/r^2, it a) must have spherical mass symmetry b) cannot be hollow inside c) must have a mass << rc^2 / (2G) d) must have constant density throughout

a) must have spherical mass symmetry

A moon is in orbit around its mother planet. Which of the following statements is always true about its kinetic energy (K), and its gravitational potential energy (U)? a) K is negative, U is negative b) K is positive, U is negative c) K is positive, U is positive d) K is negative and U is positive

b) K is positive, U is negative

Consider an Earth satellite in an elliptical orbit. Its centripetal acceleration is a) constant b) g at the satellite c) < g at the satellite d) zero e) > g at the satellite

b) g at the satellite

Kepler's 3rd law says T^2 / r^3 = K. What does the constant K depend upon? a) size b) mass c) temperature d) period e) frequency

b) mass (but of the sun)

The speed needed at the bottom of a loop-the-loop track so that a car can coast to the top, with sufficient speed to stay on the track, depends on the mass of the car. (Neglect the effects of friction.) a) sometimes true, since potential energy is a function of mass b) never true c) always true, since potential energy is a function of mass d) always true, since kinetic energy is a function of mass e) sometimes true, since kinetic energy is a function of mass

b) never true

Satellite A has twice the mass of satellite T, and rotates in the same orbit. Which of the following is true? a) the speed of T is 1/4 the speed of A b) the speed of T is equal to the speed of A c) the speed of T is twice the speed of A d) the speed of T is half the speed of A e) the speed of T is 3/4 the speed of A

b) the speed of T is equal to the speed of A

The speed of Halley's comet, while traveling in its elliptical orbit around the sun, a) is zero at two points in the orbit b) is zero at four points in the orbit c) increases as it nears the sun d) decreases as it nears the sun e) is constant

c) increases as it nears the sun

A spaceship is traveling to the moon. At what point is it beyond the pull of Earth's gravity? a) when it is 3/4 of the way there b) when it is closer to the moon than it is to Earth c) it is never beyond the pull of Earth's gravity d) when it is half-way there e) when it gets above the atmosphere

c) it is never beyond the pull of Earth's gravity

Marilyn and her sister Sheila are riding on a merry-go-round. Marilyn is on the edge of it and Sheila is at the center. Which of the following is true? a) they have the same speed and the same angular velocity b) they have different speeds and different angular velocities c) they have different speeds, but the same angular velocity d) they have the same speed, but their angular velocity is different

c) they have different speeds, but the same angular velocities

Kepler's discovery that T^2 / r^3 = K applies a) to elliptical orbits where r is the average distance b) only to circular orbits c) to orbits where K is a universal constant d) to lunar motion provided K is the same for planetary motion

c) to orbits where K is a universal constant

The following statements refer to man-made artificial satellites in orbit around Earth. Which is an accurate statement? a) the velocity required to keep a satellite in a given orbit depends on the mass of the satellite b) it is possible to have a satellite traveling at either a high speed or at a low speed in a given circular orbit c) the period of revolution of a satellite moving about the Earth is independent of the size of the orbit it travels d) a satellite in a large diameter circular orbit will always have a longer period of revolution about the Earth than will a satellite in a smaller circular orbit e) only circular orbits are possible for artificial satellites

d) a satellite in a large diameter circular orbit will always have a longer period of revolution about the Earth than will a satellite in a smaller circular orbit

James is twirling a rock around a horizontal circle on the end of a string. The motion is counterclockwise. If the speed is constant, what is the acceleration at point A? a) v/r b) rv^2 c) centrifugal d) centripetal e) zero

d) centripetal

The banking angle in a turn on the Olympic bobsled track is not constant, but increases upward from the horizontal. Coming around a turn, the bobsled team will intentionally "climb the wall" then go lower coming out of the turn. Why do they do this? a) to give the team better control, because they are able to see ahead of the turn b) to prevent the bobsled from turning over c) to reduce the g-force on them d) to take the turn at a faster speed e) to increase the g-force on them

d) to take the turn at a faster speed

Who was the first person to realize that planets move in elliptical paths around the sun? a) Einstein b) Brahe c) Copernicus d) Galileo e) Kepler

e) Kepler

A car, driven around a circle with constant speed, must have a) zero acceleration b) a tangential acceleration c) zero velocity d) a centrifugal acceleration e) a centripetal acceleration

e) a centripetal acceleration

A pilot executes a vertical dive. Just before the plane starts to come up from the bottom of the dive, the force on him is a) equal to g, and pointing down b) less than g, and pointing up c) more than g, and pointing down d) less than g, and pointing down e) more than g, and pointing up

e) more than g, and pointing up

Does the centripetal force acting on an object do work on the object? a) yes, since it takes energy to turn an object b) yes since a force acts and the object moves, and work is force times distance c) yes, because the force and the displacement of the object are perpendicular d) no, because the object has constant speed e) no, because the force and the displacement of the object are perpendicular

e) no, because the force and the displacement of the object are perpendicular

Consider a small satellite moving in a circular orbit (radius r) about a spherical planet (mass M). The period does not depend upon a) the radius r b) g at the satellite position c) the planet mass d) the universal gravitational constant e) the satellite mass

e) the satellite mass

A race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience? a) 1.0 rad/s^2 b) 10000. rad/s^2 c) 630. rad/s^2 d) 2000. rad/s^2 e) zero

e) zero