Ch. 7 Physics Test
The safe speed (no friction needed to stay on the run) for the smaller radius curve is V. Therefore, the safe speed on the larger radius curve is
1.4 V
The weight of an object on the Moon is what fraction of the weight of the same object on Earth?
1/6
Kepler's Second Law
A line joining a planet and the sun sweeps out equal areas in equal intervals of time
The following statements refer to man-made, artificial satellites in orbit around Earth. Which is an accurate statement?
A satellite in a large diameter circular orbit will always have a loner period of revolution about the Earth than will a satellite in a smaller circular orbit
Why do the two different expressions for gravitational potential energy (+mgh and -GmM/r) have different signs?
Because reference level is different
True or False: The net force on an object in its 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 in the body have the same TANGENTIAL speed
False
Imagine yourself in a car traveling around a sharp curve. The "centripetal" force is inward, yet why do you slide outward and not inward?
Inertia
Which of the following statements is always true about its kinetic energy (K), and its gravitational potential energy (U)?
K is positive, and U is negative
Kepler's Third Law
States that the square of the ratio of the periods of any two planets is equal to the cube of the ratio of their average distances from the Sun.
Kepler's First Law
The orbits of the planets are ellipses, with the sun at one focus
satellite A has twice the mass of satellite T, and rotates in the same orbit. Which following is true?
The speed of T is equal to the speed of A
Newton never knew the numerical value of "his" universal gravitational G
True
True or False: The constant in K in Kepler's Third Law is the same for all the planets in our solar system, but is 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
A car, driven around a circle with constant speed, must have
a centripetal acceleration
Kepler's 3rd law says T^2/r^3=K. What does the constant K depend upon?
frequency
Consider an Earth satellite in an elliptical orbit. Its centripetal acceleration is
g at the satellite
The speed of Halley's Comet, while traveling in its elliptical orbit around the Sun,
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?
it is never beyond the pull of Earth's gravity
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
more than g, and pointing up
For a spherical planet to act like a "point mass", so that externally F= GmM/r^2, it
must have spherical mass symmetry
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
never true
Does the centripetal force acting on an object do work on the object?
no, because the force and the displacement of the object are perpendicular
A planet is discovered to orbit around a star in the galaxy Andromeda, with the same orbital diameter as the Earth around our Sun. If that star has 4 times the mass of our Sun, what will the period of revolution of that new planet be, compared to the Earth's orbital period?
one-half as much
A satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. The acceleration of gravity at the satellite, as compared to the acceleration of gravity on the surface of Mars, is
one-sixteenth as much
If the Earth had four times its present mass, what would be its new period of revolution around the sun, compared to its present orbital period?
the same
The total energy of a circularly orbiting satellite is ______ the kinetic energy
the same as
Consider a small satellite moving in a circular orbit (radius r) about a spherical planet (mass M). The period does not depend upon
the satellite mass
Kepler's discovery that T^2/r^3=K applies
to elliptical orbits where r is the average distance
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?
to take the turn at a faster speed
