Superluminal jets. Figure 37-29a shows the path taken by a knot in a jet of ionized gas

Chapter 37, Problem 63

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Superluminal jets. Figure 37-29a shows the path taken by a knot in a jet of ionized gas that has been expelled from a galaxy. The knot travels at constant velocity at angle u from the direction of Earth. The knot occasionally emits a burst of light, which is eventually detected on Earth. Two bursts are indicated in Fig. 37-29a, separated by time t as measured in a stationary frame near the bursts. The bursts are shown in Fig. 37-29b as if they were photographed on the same piece of film, first when light from burst 1 arrived on Earth and then later when light from burst 2 arrived. The apparent distance Dapp traveled by the knot between the two bursts is the distance across an Earth-observers view of the knots path.The apparent time Tapp between the bursts is the difference in the arrival times of the light from them. The apparent speed of the knot is then Vapp Dapp/Tapp. In terms of v, t, and u, what are (a) Dapp and (b) Tapp? (c) Evaluate Vapp for v 0.980c and u 30.0. When superluminal (faster than light) jets were first observed, they seemed to defy special relativityat least until the correct geometry (Fig. 37-29a) was understood. DappBurst 1 Burst 2Path of knot of ionized gasBurst 1Burst 2DappLight raysheaded toEarth(a)(b)Figure 37-29 63.