Because each half-life is 1.5 hours, a time interval of 6 hours is equal to 4 half-lives. After each half-life elapses, the mass of the sample is cut in half, so after 4 half-lives, the mass of the sample decreases from 2 grams to 1 gram to 0.5 grams to 0.25 grams and, finally, to 0.125 grams.

The correct answer is (C). According to Coulomb's law, the force exerted by two charged bodies on one another is indirectly related to the square of the distance between them. When the distance is halved, they exert four times more force on one another.

The correct answer is (A). The higher the frequency of the light waves, the higher the energy of the photons. Of the choices presented, blue light has the highest frequency.

The correct answer is (E). The resultant vector is the distance the dog is from home. The opposite of the resultant vector is the equilibrant vector.

The correct answer is (C). The acceleration-time graph shows a time rate change in velocity. This is the definition of acceleration.

The correct answer is (D). If the input frequency of a wave system is equal to its vibrating frequency, the resonant system acts to amplify the waves, thus transferring their energy into the delicate crystal and breaking it.

The correct answer is (B). An increase in the length of the pendulum causes the period of the pendulum to increase too. . Notice the in the period equation.

The speed of the chirp is

The correct answer is (A). The geosynchronous satellite circles the earth at the same rate as the earth turns beneath it. Thus the satellite stays in the same position relative the earth.

The correct answer is (D). The product of the frequency and the wavelength can be obtained by the dimensional analysis. V = λf , which yields

The correct answer is (B). The sound waves from the approaching whistle strike the listener's ears at an increasing rate, producing the increasing pitch.

The equation for volume expansion is ∆V = delta VVi∆T, so

Applying Coulomb's law, we see that the electric force will not change.

The correct answer is (C). This is a work-energy problem. PE = Work → mgh = F·D. Rearrange, substitute, and solve (remember m·g = wt):

If the photons of the incident light have insufficient energy to liberate electrons from the metal's surface, then simply increasing the number of these weak photons (that is, increasing the intensity of the light) will do nothing. To produce photoelectrons, each photon of the incident light must have an energy at least as great as the work function of the metal.

The correct answer is (B). Both spheres fall from the same height. This means the objects are in free fall, so their accelerations are the same. Sphere B has more mass than sphere A, which gives sphere B more momentum and more kinetic energy when the two spheres reach the ground.

The correct answer is (E). At STP the molar volume of any gas is 22.4 L. Standard pressure and volume are also the same for all gases, and of course a mole of any substance is the same number of particles.

Redshift occurs when light sources move away from the observer. If all the galaxies in the universe are moving away from us, that's evidence that the universe is expanding. The Uncertainty Principle is a quantum mechanical phenomenon having to do with subatomic particles, not galaxies. The evidence that black holes exist is their gravitational effects on visible objects near them, not redshift. Dark matter has to do with anomalous rotation curves in galaxies, not redshift (though redshift ”specifically, increasing redshift ”is evidence for dark energy). Superconductivity has to do with conducting electricity, not galaxies.

The correct answer is (C). Your image is standing upright. Your feet and the image of your feet are down, and your head and the image of your head are up. When you raise your right hand, the left hand of the image is raised. This is a reversal of left and right.

The correct answer is (D). The first law of thermodynamics can be stated as:

From the equations λf = v and f = I/T, we get λ = vT = 2(cm/s)(2 s) = 4 cm.

With crate #2 on top of crate #1, the force pushing downward on the floor is greater, so the normal force exerted by the floor on crate #1 is greater, which increases the friction force. B, C, D, and E are all false.

The correct answer is (D). According to Newton's Third Law, the action-reaction force pair must be equal in magnitude and oppositely directed. The earth pulls on the mass, and the mass pulls on the earth (the pair) with the same force.

The correct answer is (E). The only pair of charged bodies that would attract one another is the pair of unlike charged spheres.The rest of the pairs are like charges, which repel one another.

The correct answer is (A). The ratio between the number of turns in the primary and the number of turns in the secondary is equal to the ratio of the primary voltage and the secondary voltage 120V/24V = 5:1.

The correct answer is (B). The acceleration of the skydivers continues to decrease until the terminal velocity of the group is reached. When the air resistance reaches the point where it exactly balances the force exerted on the divers by the earth's gravitational attraction, their acceleration becomes zero.

The correct answer is (D). The larger amount of padding in the amateur gloves causes the time of impact to be increased, which results in less force being exerted.

The correct answer is (C). The moon is only 1/6 the size of the earth, so at a distance 55% of the way to the moon, the object is still under the influence of the earth's gravitational field. That means the object will eventually fall back to the earth.

The correct answer is (E). An adiabatic expansion is a process in which no heat flows into or out of the system. During an adiabatic expansion the gas cools as it expands and does work.

The correct answer is (E). The electron carries a negative charge of 1.6e-19C, which is a tiny amount of energy. The electron volt is the energy required to move 1 electron through an electric potential of 1 volt.

By combining the equation for centripetal acceleration, ac = v2/r, with v = rω, we find

The correct answer is (D). The de Broglia wavelength cannot be detected because the objects in question have velocities that are too small for the waves they create to be detectable.

The correct answer is (D). The frequency at which the humming bird beats its wings is already given in beats per minute. To find the number of wing beats per second (Hz), divide the number of wing beats per minute by 60 seconds.

The correct answer is (E). Pressure is the measure of the rate at which the gas particles collide with the sides of the containers. The more often the gas particles collide with the container walls, the higher the pressure.

First, the kinetic energy the block gains is the same as the potential energy it loses, which is mgh. Since this is equal to mv2, we find that v = . Plugging in g = 10 m/s2 and h = 4 m, we get v = ≈ 9 m/s.

Since the velocity does not change, the acceleration of the box is zero, so the net force the box feels must also be zero. Since the mover pushes on the box with a force of 200 N, the force of kinetic friction must also be 200 N (in the opposite direction) to give a net force of zero. Because the strength of the force of kinetic friction, Ffriction, is equal to μFN, where FN = mg (since the floor is flat), we find that

The correct answer is (C). All objects in free fall near the earth are accelerated toward the earth at the same rate. Even though the car is moving along the x-axis at a high rate of speed, as soon as it clears the edge of the cliff it is in free fall. Both the rock and the car start with a y velocity of zero and reach the ground at the same time.

The magnetic field lines created by a long, straight, current-carrying wire are circles centered on the wire.

The maximum force that static friction can exert on the crate is μsFN = μsFw = μs mg = (0.4)(100 kg)(10 N/kg) = 400 N. Since the force applied to the crate is only 344 N, static friction is able to apply that same magnitude of force on the crate, keeping it stationary. [B is incorrect because the static friction force is not the reaction force to F; both F and Ff (static) act on the same object (the crate) and therefore cannot form an action/reaction pair.]

The correct answer is (D). According to the first law of thermodynamics, the internal heat of the system remains the same unless work is done or heat is added to the system. Neither of those two things occurs, so the system of two objects, one hot and one cold, transfers heat between itself with the hot object losing to the cold object until thermal equilibrium is reached.