Questions: A nucleus moving at a speed of 2.5 × 10^8 m / s crashes into a device that measures its kinetic energy to be 1.24 × 10^-9 J.
What is the mass of this nucleus?
Transcript text: A nucleus moving at a speed of $2.5 \times 10^{8} \mathrm{~m} / \mathrm{s}$ crashes into a device that measures its kinetic energy to be $1.24 \times 10^{-9} \mathrm{~J}$.
What is the mass of this nucleus?
Solution
Solution Steps
Step 1: Identify the Known Variables
We are given the speed of the nucleus, \( v = 2.5 \times 10^8 \, \text{m/s} \), and its kinetic energy, \( KE = 1.24 \times 10^{-9} \, \text{J} \).
Step 2: Use the Kinetic Energy Formula
The formula for kinetic energy is:
\[
KE = \frac{1}{2} m v^2
\]
where \( m \) is the mass of the nucleus.
Step 3: Solve for Mass
Rearrange the kinetic energy formula to solve for mass \( m \):
\[
m = \frac{2 \times KE}{v^2}
\]
Step 4: Substitute the Known Values
Substitute the given values into the equation:
\[
m = \frac{2 \times 1.24 \times 10^{-9} \, \text{J}}{(2.5 \times 10^8 \, \text{m/s})^2}
\]
Step 5: Calculate the Mass
Calculate the mass:
\[
m = \frac{2.48 \times 10^{-9}}{6.25 \times 10^{16}}
\]
\[
m = 3.968 \times 10^{-26} \, \text{kg}
\]
Final Answer
The mass of the nucleus is \(\boxed{3.968 \times 10^{-26} \, \text{kg}}\).