Consider a source of radiation with a luminosity of 8x104 lo located at a distance of 2 kpc. (a) assume that the light has a wavelength of λ 550 nm. how many photons per second does the keck telescope receive from this source (the diameter of keck is 10 m)? (b) if this source were to emit in the x-rays, with photons that have an energy~1 kev, how many photons per second would the chandra x-ray ( )beorea ory texx: lve the aroa of chandra about 0.h

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?