Imagine that you see an enormous explosion out in space. This explosion puts out a total energy of 1044 J, and lasts for a week. Detailed observations show that this explosion did not blast any gas into space, even though there was plenty of hydrogen close to the exploding object. What is the minimum possible mass of the thing that exploded (in kg)? You may assume that G=6.67×10−11N m2 kg−2 , c=3.0×108m s−1 , mp=1.67×10−27kg , h=6.63×10−34m2 kg s−1 and σT=6.7×10−29m2 . You may also assume that the explosion had a constant brightness throughout the week.

What is the electric force acting between two charges of -0.0045 c and -0.0025 c that are 0.0060 m apart? use fe=kq1q2/r^2 and k = 9.00 x 10^9 n*m^2/c^2 a. 1.7 x 10^7 n b. -1.7 x 10^7 n c. -2.8 x 10^9 n d. 2.8 x 10^9 n

An object with initial temperature 130 ∘ f is submerged in large tank of water whose temperature is 50 ∘ f . find a formula for f ( t ) , the temperature of the object after t minutes, if the cooling constant is k = − 0.2 . remember newton's law of cooling (the rate of change of temperature with respect to time is equal to k times the difference between the temperature of the object and the surrounding temperature) ! : )

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.