A solid sphere of mass 0.750 kg and radius 5.00 cm is spun up to an angular velocity 10.0 rad/s, spinning clockwise. The sphere is held just barely above a flat platform of mass 5.00 kg, then released onto the platform. The sphere begins to skid and moves along the platform until it rolls without slipping. The coefficient of kinetic friction between the sphere and the platform is 0.70. The coefficient of friction between the platform and the ground is 0.05, and the platform begins to slide across the ground. Find an expression for the horizontal position of the center of mass of the sphere as a function of time (hint—it’s piecewise!), and note the times at which the sphere’s motion changes.

A1kg cart slams into a stationary 1kg cart at 2 m/s. the carts stick together and move forward at a speed of 1 m/sl. determine whether kinetic energy was conserved in the collision. use the law of conservation of energy to explain the collision

Chapter 23, problem 075 the figure shows a geiger counter, a device used to detect ionizing radiation (radiation that causes ionization of atoms). the counter consists of a thin, positively charged central wire surrounded by a concentric, circular, conducting cylindrical shell with an equal negative charge. thus, a strong radial electric field is set up inside the shell. the shell contains a low-pressure inert gas. a particle of radiation entering the device through the shell wall ionizes a few of the gas atoms. the resulting free electrons (e) are drawn to the positive wire. however, the electric field is so intense that, between collisions with gas atoms, the free electrons gain energy sufficient to ionize these atoms also. more free electrons are thereby created, and the process is repeated until the electrons reach the wire. the resulting "avalanche" of electrons is collected by the wire, generating a signal that is used to record the passage of the original particle of radiation. suppose the radius of the central wire is 24 âµm, the inner radius of the shell 2.3 cm, and the length of the shell 14 cm. if the electric field at the shell's inner wall is 2.8 ă— 104 n/c, what is the total positive charge on the central wire?

What is the energy of a photon of ultraviolet radiation with a frequency of 4.4 × 1015 hz? planck’s constant is 6.63 × 10–34