48.
Step 1: Use the standard SHM equation
[4pt]
For simple harmonic motion,
\[
v^2=\omega^2(A^2-x^2)
\]
where:
\[
\omega = \text{angular frequency}, \qquad A = \text{amplitude}
\]
Step 2: Compare with the given equation
[4pt]
Given:
\[
v^2=50-x^2
\]
Comparing with
\[
v^2=\omega^2(A^2-x^2)
\]
we get:
\[
\omega^2=1
\]
Hence,
\[
\omega=1\ \text{rad/s}
\]
Also,
\[
A^2=50
\]
\[
A=\sqrt{50}
\]
Step 3: Find the time period
[4pt]
The time period of SHM is:
\[
T=\frac{2\pi}{\omega}
\]
Substituting \(\omega=1\):
\[
T=2\pi
\]
Using
\[
\pi=\frac{22}{7}
\]
\[
T=2\times\frac{22}{7}
\]
\[
T=\frac{44}{7}\text{ s}
\]
Step 4: Compare with given time period
[4pt]
Given:
\[
T=\frac{x}{7}\text{ s}
\]
So,
\[
\frac{x}{7}=\frac{44}{7}
\]
Multiplying both sides by \(7\):
\[
x=44
\]
Final Answer:
\[
\boxed{x=44}
\]