Question

Bianca is standing at $x=600m$.Firecracker $1$at the origin, and firecracker$2$, at $x=900m$explode simultaneously. The flash from firecracker$1$ reaches Bianca’s eye at $t=3.0\mu s$.At what time does she see the flash from firecracker$2$?

Short answer

Bianca will observe the flash at $t=3\mu s$from firecracker$2$.

Step-by-step solution

Given Information

We have given that, Bianca is standing at $x=600m$.

Firecracker $1$, at the origin, and firecracker $2$at $x=900m$, explode simultaneously.

The flash from firecracker reaches Bianca’s eye at$t=3.0\mu s$.

Simplify

Bianca is standing at $x=600m$.

The distance between the starting point and Bianca is $600m$.

The time taken to reach Bianca's eyes is as below

$$\begin{gathered} t=\frac{600}{\text{sppedoflight}} \\ t=\frac{600}{3\times {10}^8} \\ t=2\times {10}^{-6}s \\ t=2\mu s \end{gathered}$$

Cracker exploded at time $t=2\mu s$because it was seen at time $t=4\mu s$.

The time taken by 2nd cracker flash to reach Bianca eyes

$$\begin{gathered} t_2=\frac{300}{3\times {10}^8} \\ {t}_2={10}^{-6} \\ {t}_2=1\mu s \end{gathered}$$

Therefore, Bianca will observe the flash at $t=3\mu s$.