A lens of focal length f is used to project an image of a solar eclipse on a flat sheet of paper. Which of the following image distances gives the clearest image in this case?
The half-life of radioactive Technetium-99 is 6.0 hours. Find the number of 99Tc nuclei necessary to produce a sample of activity 18 µCi. (1 Ci = 3.7 × 10^10 decays/second)
It is often possible to use atomic masses when calculating the binding energy of a nucleus. This is not true for calculating the Q value for the e+ decay process since
Velocity: A light-year is the distance that light travels in one year. The speed of light is 3.00 × 108 m/s. How many miles are there in one light-year? (1 mi = 1609 m, 1 y = 365 d)
Two loops of wire are arranged so that a changing current in one, the primary, will induce a current in the other, the secondary. The secondary loop has twice as many turns as the primary loop. The current in the primary at this moment is 3 A and increasing. The current in the secondary must be
Power: A simple circuit has a total resistance of 30 Ω. If a 2.0-A current is maintained in this circuit, how much energy is dissipated in this circuit in 4.0 seconds?
Torque: A flat circular loop of wire of radius 0.50 m that is carrying a 2.0-A current is in a uniform magnetic field of 0.30 T. What is the magnitude of the magnetic torque on the loop when the plane of its area is perpendicular to the magnetic field?
A skydiver jumps out of a hovering helicopter. A few seconds later, another skydiver jumps out, so they both fall along the same vertical line relative to the helicopter. Both skydivers fall with the same acceleration. (Assume g is constant.) The difference in their velocities
A 0.60-kg rock is swung in a circular path and in a vertical plane on a 0.25-m length string. At the top of the path, the angular speed is 12.0 rad/s. What is the tension in the string at that point?
A light body sliding on a smooth horizontal surface collides with a heavy body. During the instant of contact the force exerted by the light body on the heavy body is ________ (equal to, greater than, less than) the force exerted by the heavy body on the light body.
Intensity of Sound: A barking dog delivers about 1.0 mW of power, which is assumed to be uniformly distributed in all directions. What is the intensity level in decibels at a distance 5.00 m from the dog? The threshold of human hearing is 1.0 × 10-12 W/m2.
The plates of a parallel-plate capacitor are maintained with constant voltage by a battery as they are pulled apart. What happens to the magnitude of the field between the plates during this process?
You are standing in a moving bus, facing forward, when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward?
A series of weights connected by very light cords are given an upward acceleration of 4.00 m/s2 by a pull P, as shown in the figure. A, B, and C are the tensions in the connecting cords. The pull P is closest to
If a Σ- particle at rest decays into a neutron and a π- , what is the total kinetic energy of the decay products? The masses of Σ-, neutron, and π- are 1197 MeV/c2, 940 MeV/c2, and 140 MeV/c2, respectively
Two identical arrows, one with twice the kinetic energy of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates
Suppose an object is placed 6.0 cm in front of a lens that has a focal length of 4.0 cm. Where is the image located? What are the magnification and the character of the image?
Thin Lenses: When an object is placed 118 cm from a thin diverging lens, its image is found to be 59 cm from the lens. The lens is removed, and replaced by a thin converging lens whose focal length has the same magnitude as the diverging lens. This second lens is at the original position of the first lens. Where is the image of the object now?
While standing at a crosswalk, you hear a frequency of 600 Hz from an approaching police car. After the police car passes, its frequency is 400 Hz. What is the speed of the police car? (speed of sound = 340 m/s)