Question

A neutron, one of the constituents of a nucleus, is found to pass two points $60$ meters apart in a time interval of $1.8\times {10}^{-4}$ sec. The mass of a neutron is $1.7\times {10}^{-27}$ kg. Assuming that the speed is constant, its kinetic energy is:

• A. $9.4\times {10}^{-16}J$
• B. $9.3\times {10}^{-14}J$
• C. $9.3\times {10}^{-21}J$
• D. $9.3\times {10}^{-11}J$

Answer 1

The correct option is A $9.4\times {10}^{-16}J$

Since speed is constant:

$speed=\frac{Distance}{time}=\frac{60}{1.8\times {10}^{-4}}=\frac{{10}^6}{3}$

$K.E=\frac{1}{2}m{v}^2$

$=\frac{1}{2}\times 17\times {10}^{-27}\times (\frac{{10}^6}{3}{)}^2$

$=9.4\times {10}^{-16}J$