Achild of mass 3m sits on a swing, the base of which has mass m, while the rope (of length l) q34. has a negligible mass. an adult pulls back the swing (with the child) until the rope makes an angle of half-a-radian with the vertical, and, then, pushes with a force mg along the arc of a circle until the rope is exactly vertical and releases it. if the rope was always taut, for how long did the adult push? 20 (а) л 3g 20 (d) 3g (b) 3 g g q49. two tuning forks with natural frequencies v, and v, respectively, are struck at the same time with equal force. the intensity, of the resulting sound, waxes and wanes with time period of 1.5 seconds while the frequency of the sound is 256 hz. hence v, and v, respectively are (a) 256.333 hz and 255.667 hz (b) 256.55 hz and 255.55 hz (d) 256.5 hz and 257 hz (c) 256 hz and 256.5 hz

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?

Steam is generated in a boiler of a cogeneration plant at 10 mpa and 450°c at a steady rate of 5 kg/s. in normal operation, steam expands in a turbine to a pressure of 0.5 mpa and is then routed to the process heater, where it supplies the process heat. steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. in this mode, no steam passes through a condenser, which operates at 20 kpa. (a) determine the power produced in the turbine and the rate at which process heat is supplied in this mode. (b) determine the power produced in the turbine and the rate of process heat supplied if only 60 percent of the steam is routed to the process heater and the remainder is expanded to the condenser pressure. (3.32 mw; 9.69 mw; 4.25 mw; 5.82 mw)

For the car in the picture ,in which direction is the normal force? -into the screen -down -out of the screen -up