A stellar black hole may form when a massive star dies. The mass of the star collapses down to a single point. Imagine an astronaut orbiting a black hole having five times the mass of the Sun. Assume the orbit is circular. (a) Find the speed of the astronaut if his orbital radius is r = 1 AU. 66.99 Your response is off by a multiple of ten. m/s (b) Find his speed if his orbital radius is r = 7.4 km. 3 Your response differs significantly from the correct answer. Rework your solution from the beginning and check each step carefully. m/s (c) CHECK and THINK: Compare your answers to the speed of light in a vacuum. What would the astronaut's orbital speed be if his orbital radius were smaller than 7.4 km? The light speed is represented by B component. Even light won't be able to leave the orbit if the orbital radius is smaller than 7.4 km. If the radius is decreased by more than 7.4 km, the orbital speed will increase. Score: 1.68 out of 1.68 Comment: