A40-l electrical radiator containing heating oil is placed in a 60-m3 room as shown in the figure. both the room and the oil in the radiator are initially at 10°c. the radiator with a rating of 2.4 kw is now turned on. at the same time, heat is lost from the room at an average rate of 0.35 kj/s. after some time, the average temperature is measured to be 20°c for the air in the room, and 50°c for the oil in the radiator. taking the density and the specific heat of the oil to be 950 kg/m3 and 2.2 kj/kg·°c, respectively, determine how long the heater is kept on. assume the room is well-sealed so that there are no air leaks. the gas constant of air is r = 0.287

The frequency of vibrations of a vibrating violin string is given by f = 1 2l t ρ where l is the length of the string, t is its tension, and ρ is its linear density.† (a) find the rate of change of the frequency with respect to the following. (i) the length (when t and ρ are constant) (ii) the tension (when l and ρ are constant) (iii) the linear density (when l and t are constant) (b) the pitch of a note (how high or low the note sounds) is determined by the frequency f. (the higher the frequency, the higher the pitch.) use the signs of the derivatives in part (a) to determine what happens to the pitch of a note for the following. (i) when the effective length of a string is decreased by placing a finger on the string so a shorter portion of the string vibrates df dl 0 and l is ⇒ f is ⇒ (ii) when the tension is increased by turning a tuning peg df dt 0 and t is ⇒ f is ⇒ (iii) when the linear density is increased by switching to another string df dρ 0 and ρ is ⇒ f is ⇒

What are the starting materials for nuclear fission? two small nuclei two large nuclei a neutron and a large nucleus a neutron and a small nucleus

What is the orbital period of a spacecraft in a low orbit near the surface of mars? the radius of mars is 3.4×106m.