A star ending its life with a mass of four to eight times the Sun's mass is expected to collapse and then undergo a supernova event. In the remnant that is not carried away by the supernova explosion, protons and electrons combine to form a neutron star with approximately twice the mass of the Sun. Such a star can be thought of as a gigantic atomic nucleus. Assume r-aA1/3. If a star of mass 3.88 x 1030 kg is composed entirely of neutrons (mn 1.67 x 1027 kg), what would its radius be?

r = 16 Km

Explanation:

given  

m_n= 1.67 x 10^-27 Kg

M_star = 3.88 x 10^30 Kg  

A= M_star/m_n

A= 3.88*10^30/1.67 x 10^-27

A=2.28 *10^57  neutrons                           A = The number of neutrons  

we use the number of neutrons as a mass number because the star has only neutrons. = 1.2 x 10-15 m

r = r_o*A^1/3

r = 1.2*10^-15*2.28 *10^57^1/3

r = 16 Km

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27