21.49 .. a charge of -6.50 nc is spread uniformly over the surface of one face of a nonconducting disk of radius 1.25 cm. (a) find the magnitude and direction of the electric field this disk produces at a point p on the axis of the disk a distance of 2.00 cm from its center. (b) suppose that the charge were all pushed away from the center and distributed uniformly on the outer rim of the disk. find the magnitude and direction of the electric field at point p. (c) if the charge is all brought to the center of the disk, find the magnitude and direction of the electric field at point p. (d) why is the field in part (a) stronger than the field in part (b)? why is the field in part (c) the strongest of the three fields?

Air is held within a frictionless piston-cylinder container, which is oriented vertically. the mass of the piston is 0.45 kg and the cross-sectional area is 0.0030 m2. initially (state 1) the pressure of the gas is sufficient to support the weight of the piston as well as the force exerted by the atmospheric pressure ( 101.32 kpa). the volume occupied by the air within the cylinder in state 1 is 1.00 liter. one end of a spring (with spring constant k = 1000 n/m) is attached to the top of the piston, while the other end of the spring is attached to a stage that can move vertically. initially the spring is undeflected and therefore exerts no force. then the stage is then moved quasistatically downward a distance of 10.0 cm, at which point the system reaches state 2. the piston-cylinder is not insulated; rather it remains in diathermal contact with the surroundings, which are at a constant temperature of 300 k. what is the change of pressure within the container?

Aspecimen of oil having an initial volume of 580cm^3 is subjected to a pressure increase of 4.0 mpa, and the volume is found to decrease by 0.40 cm^3. (a) what is the bulk modulus of the material? (b) what is the compressibility of the material?

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?