Answer
$5.3\times 10^{-11}m$
Work Step by Step
The uncertainty in the velocity is given in the problem. Calculate the uncertainty in the position by using equation 28–1.
$$\Delta x \geq \frac{\hbar}{\Delta p}=\frac{\hbar}{m \Delta v}$$
$$=\frac{1.055\times 10^{-34}J \cdot s}{(1.67\times10^{-27}kg)(1200m/s)}$$
$$=5.3\times 10^{-11}m$$