8/20:
1:  The number of significant figures in the result of a calculation should be equal to the number of significant figures of the least accurate of the quantities entering into the calculation.
2.  The slope of the curve in a position vs. time graph for a particle's motion gives the particle's instantaneous velocity.
3.  The displacement of a particle is its total change in position.

8/23:
1.  Is it possible for an object's instantaneous velocity and instantaneous acceleration to be of opposite sign at the same instant of time?  Yes
2.  A ball is thrown downward (not dropped) from the top of a tower.  Neglecting air resistance, after being released, its downward acceleration is exactly equal to g.
3.  The equation x = x₀ + v₀t + (1/2)at² can be used only if the acceleration is constant.

8/25:
1.  If you multiply a vector A (of magnitude A) by a scalar c, the result is a vector whose magnitude is cA.
2.  If you multiply a vector A (magnitude A) by another vector B (magnitude B), the result is not covered in the reading assignment.
3.  An inertial reference frame is a reference frame that is not accelerated.

8/27:
1.  Without air resistance, an object dropped from a plane flying at constant speed in a straight line will remain vertically under the plane.
2.  The path in space of a projectile launched at an angle to the vertical, moving under the influence of gravity is a parabola.
3.  The effect of an acceleration that is always perpendicular to the velocity is a change in only the direction of the velocity.

8/30:
1.  If an object is undergoing uniform circular motion, it moves in a circle with constant speed.
2.  If an object is undergoing uniform circular motion, it moves in a circle with acceleration that varies in direction but not in magnitude.
3.  If an object is undergoing non-uniform circular motion, its radial and tangential acceleration are always perpendicular. (In fact, radial and tangential acceleration are always perpendicular, regardless of whether the motion is uniform or not. In the uniform case, the tangential accleration is zero.)

9/1:
1.  The net force is the vector sum of all forces acting on an object.
2.  The law of inertia expresses the tendency of bodies to maintain their state of motion.
3.  Impulse is not covered in the reading assignment. (But see Chap. 11.)

9/3:
1.  Astronauts on the Moon can jump so high because they weigh less there than they do on Earth.
2.  If two objects are subject to the same force, the one that will experience the greater acceleration is the one with the smaller mass.
3.  The units of weight in the SI system are newtons.

9/8:
1.  The normal force on a body is always directed perpendicular to the surfaces in contact.
2.  Is the normal force on a body always equal to its weight? No.
3.  Hooke's law states that the force exerted by a spring is proportional to the amount by which it is stretched or compressed.

9/10:
1.  A free-body diagram shows all the forces that act on an object.
2.  A rope that can be considered to be massless has the same tension throughout its length.
3.  The centripetal force is not covered in the reading assignment. (But see section 6.3.)

9/15:
1.  In a roller-coaster ride that executes a loop-the-loop (where the car carrying the passengers goes completely upside-down at the top of a vertical circle), the force providing the centripetal acceleration is the normal force of contact. (Note that gravity has a centripetal component during the upper half of the circle, but the rest of the time it provides a force that points away from the center.)
2.  In a banked curve on a road, the force providing the centripetal acceleration is the normal force of contact. (Friction, if present, will also contribute.)
3.  When a car rolls over the crest of a hill, the force that keeps it in contact with the road (so that it follows the arc of the road surface) is provided by gravity.

9/17:
1.  If you push a heavy object and it does not move, the force of static friction is equal to the force with which you are pushing.
2.  When you walk, the force that causes you to accelerate forward is the force of static friction exerted by the ground on your foot.
3.  The coefficient of friction has no units--it is dimensionless.

9/20:
1.  A woman holds a bowling ball above the floor in a fixed position. The work she does on the ball is zero.
2.  A man pushes a heavy load across a horizontal floor. The work done by gravity on the load is zero.
3.  A ball is thrown straight upward into the air. The work done by gravity on the ball before it reaches the top of its trajectory is negative.

9/22:
1.  When you do positive work on an object, its kinetic energy increases.
2.  The SI unit of energy is the joule.
3.  Power is the rate of doing work.

9/24:
1.  Which of the following is not a conservative force? the force of friction.
2.  The gravitational potential energy of a particle at a height z above the Earth's surface depends on the height z.
3.  The potential energy of a spring is proportional to the square of the amount the spring is stretched or compressed.

9/27:
1.  Suppose you know the potential energy function corresponding to a force. Is it always possible to calculate the force? yes
2.  If the potential energy curve is very steep at a certain point (changes rapidly over a short distance), this means that the force at that point is large.
3.  The famous equation E = mc^2 expresses the principle of conservation of mass-energy.

9/29:
1.  The gravitational constant G is none of the above.
2.  Which is one of Kepler's laws? The radial line segment from the Sun to a planet sweeps out equal areas in equal time intervals.
3.  Cavendish's famous experiment determined the value of G.

10/1:
1.  A geosynchronous orbit is an orbit with a period of one day.
2.  The orbits of most of the planets in the solar system are elliptical and nearly circular.
3.  Kepler's third law for circular orbits relates the radius of the orbit to its period.

10/4:
1.  The gravitational potential energy of a person on the surface of the Earth is lower than that of the same person in orbit around the Earth.
2.  The escape speed of a rocket launched from Earth is not proportional to any of the quantities listed. (It is proportional to the square root of mass of the Earth and the inverse of the square root of the radius of the Earth.)
3.  Tidal forces on the Earth result primarily from the variation of the gravitational pull of the Moon with distance.

10/6:
1.  The center of mass of a rigid object of arbitrary shape can lie outside the object.
2.  The center of mass of a collection of objects acted on by no net external force moves according to Newton's laws as if all the mass were at the center of mass, and will have no acceleration if the sum of the external forces acting on the objects is zero.
3.  The forces that parts of an extended object exert upon one another cancel one another due to Newton's 3rd law.

10/8:
1.  Compared with the kinetic energy of its center of mass, the total kinetic energy of a system is always greater than or equal to the kinetic energy of the center of mass.
2.  A rocket is propelled forward by ejecting gas at high speed. The forward motion is a consequence of conservation of momentum.
3.  Whether a force is internal or external to an object depends on how the particular system is defined.

10/13:
1.  The impulse delivered to a body by a force is equal to the change in momentum of the body.
2.  In an elastic collision both momentum and energy are conserved.
3.  In an inelastic collision momentum is conserved.

10/18:
1.  In two-dimensional elastic collisions, the conservation laws place restrictions on possible final motions.
2.  The impact parameter is a measure of by how much the collision differs from being head-on.
3.  If a collision is viewed in the center-of-mass frame, the particles always come out back-to-back, though their directions may change.

10/20:
1.  When a disk rotates counter-clockwise at a constant rate about a vertical axis through its center, the angular acceleration of a point on the rim is zero.
2.  When a force F acts on a body, the perpendicular distance between the line of action of F and the origin of coordinates is called the lever arm.
3.  The angular quantity corresponding to the linear position (x) is angle (theta).

10/22:
1.  The moment of inertia of a rigid body is a measure of its resistance to changes in rotational motion, depends upon the axis of rotation, and is large if most of the body's mass is located far from the axis of rotation.
2.  The moment of inertia of a rigid body about a fixed axis through its center of mass is I. The moment of inertia of this same body about a parallel axis through some other point is always larger than I.
3.  Compared to the kinetic energy in a frame in which the center of mass of a rotating body is moving, the kinetic energy of that body in a frame in which the center of mass is at rest is always smaller.

10/25:
1.  A disk rolls without slipping along a horizontal surface. The center of the disk has a translational speed v. The uppermost point on the disk has a translational speed 2v.
2.  A disk rolls without slipping on a horizontal surface. The center of the disk has a translational speed v. The lowermost point on the disk has a translational speed 0.
3.  The force that allows an object to roll without slipping is static friction.

10/27:
1.  The magnitude of the cross product of two vectors A and B is equal to or smaller than the product of the magnitudes of the two vectors.
2.  If an object is rotating about a fixed axis and slowing down, its angular velocity vector omega and its angular acceleration vector alpha are antiparallel.
3.  If a disk is rotating counterclockwise about an axis that points along the +z direction, a force applied to the edge of the disk and pointing in the +z direction will cause the axis of rotation to move away from +z and toward some other direction which depends on the point at which the force was applied (i.e. any of the answers given is acceptable).

10/29:
1.  The angular momentum of a particle is zero when its position and momentum vectors are parallel.
2.  The equation of motion for a rotating body, tau = derivative of L with respect to t can be derived from Newton's laws.
3.  An ice-skater spins about a vertical axis through her body with her arms held out. As she draws her arms in, her angular velocity increases.

11/1:
1.  Polaris will someday not be the North Star. The underlying cause of this is the gravitational torque produced by the Sun and Moon on the Earth.
2.  The relationship between the precessional speed and the angular momentum capomega = mgd/L of a gyroscope holds only if the rotational speed omega is much larger than the precessional speed capomega.
3.  The gravitational torque applied to a gyroscope causes rotation about its support point.

11/3:
1.  Static equilibrium means that the net force and the net torque on a body are zero and it is at rest.
2.  The center of gravity is the point on a body where the gravitational force can be considered to act.
3.  The net torque on a body in equilibrium neither depends on the point about which the torques are calculated nor is it not zero if the body is rotating.

11/5:
1.  A shoebox (i.e. a rectangular parallopiped) is in stable equilibrium if it rests on the bottom or top (i.e. a large face).
2.  A saddle point is a configuration in which the potential energy decreases in one direction and increases in another, and a location in space where the potential energy curve is shaped like a saddle.
3.  In an object in stable equilibrium the magnitude of the supporting forces can be much larger than the weight of the object.

11/10:
1.  The time interval for one repetition of the cycle in simple harmonic motion is called the period.
2.  The frequency of an oscillator consisting of a mass on a spring depends on the spring constant and the mass.
3.  In the expression x(t) = Acos(omega*t + phi), the name given to the quantity phi is the phase constant.

11/12:
1.  The total energy of a frictionless mass-spring oscillator is constant.
2.  Two perpendicular oscillatory motions at the same frequency will combine to produce uniform circular motion if their phases differ by pi/2 or 3pi/2.
3.  The kinetic energy of an oscillator is at a maximum when the oscillator is at its equilibrium point.

11/15:
1.  When disturbed from equilibrium, an underdamped oscillator oscillates with steadily decreasing amplitude as it returns to equilibrium.
2.  A damped, driven oscillator has an oscillation frequency equal to the frequency of the driving force.
3.  The resonant frequency of a damped, driven oscillator is equal to the natural frequency.

11/17:
1.  A transverse wave propagates along a string. Each piece of the string moves perpendicular to the direction of propagation of the wave.
2.  The wave number of a wave is inversely proportional to its wavelength.
3.&npsp; A pulse is a single, isolated disturbance in a medium. (It is also the edible seed of a pod-bearing plant such as a bean.)

11/19:
1.  The expression v = sqrt(F/mu) for the wave speed on a stretched string is valid for small amplitudes.
2.  The energy carried by a wave on a stretched string moves parallel to the string, in the direction of propagation of the wave.
3.  The intensity of the wave is equal to its power divided by the area of the wavefront.

11/22:
1.  The term dispersion refers to the change in shape of a complex waveform.
2.  When two waves interfere in two dimensions, a nodal line appears wherever the difference between the distances travelled by the two waves is equal to half a wavelength.
3.  If two functions y = f(x,t) and y = g(x,t) are both solutions of the same wave equation, then f + g and 2f - 5g is also a solution.

11/24:
1.  The following characterize sound waves in air: they are longitudinal, the restoring force is provided by air pressure, and the density of the air molecules oscillates in space.
2.  The speed of sound waves in a solid depends on the density of the solid and the compressibility of the solid.
3.  The sound intensity level of a wave, measured in decibels, is proportional to the logarithm of the ratio of the intensity of the wave to a reference intensity.

11/29:
1.  A standing sound wave in a tube having one open end has a displacement node at the closed end and antinode at the open end.
2.  You are standing on a platform at the railway station. The train approaches the platform blowing its whistle, but does not stop. As the train passes you, the pitch of its whistle decreases.
3.  Shock waves are formed when the source moves faster than the speed of the wave in the medium.

12/1:
1.  A fluid is anything that flows.
2.  A static fluid in a container is subject to both atmospheric pressure at its surface and the Earth's gravitation. The pressure at the bottom of the container depends on the height of the fluid column.
3.  The buoyant force on an immersed body has the same magnitude as the weight of the fluid displaced by the body.

12/3:
1.  The equation of continuity says that the velocity of fluid flow in a pipe is inversely proportional to the cross-sectional area only for an incompressible fluid.
2.  Bernoulli's equation is a conservation law for energy.
3.  When the velocity of a fluid flow increases, pressure decreases. This relationship is expressed by Bernoulli's equation.