A newspaper delivery boy is riding his bicycle down the street at 5.0 m/s. He can throw a paper at a speed of 8.0 m/s. What is the paper's speed relative to the ground if he throws the paper (a) forward, (b) backward, and (c) to the side?
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35. Special Relativity
Special Vs. Galilean Relativity
Problem 24a
Textbook Question
Reference frame S' moves at speed v = 0.88c in the +x direction with respect to reference frame S. The origins of S and S' overlap at t = t' = 0. An object is stationary in S' at position x' = 100m. What is the position of the object in S when the clock in S reads 1.00 μs according to the Galilean?

1
Step 1: Understand the problem. We are tasked with finding the position of an object in reference frame S when the clock in S reads 1.00 μs. The object is stationary in S' at position x' = 100 m. The relative velocity between the frames is v = 0.88c. We will solve this using both (a) Galilean transformations and (b) Lorentz transformations.
Step 2: Recall the Galilean transformation equations. In Galilean relativity, time is absolute, and the position in frame S is given by: . Here, x' = 100 m, v = 0.88c, and t = 1.00 μs. Substitute these values into the equation to find x.
Step 3: Recall the Lorentz transformation equations. In special relativity, the position in frame S is given by: . Here, x' = 100 m, v = 0.88c, and t = 1.00 μs. Substitute these values into the equation to find x.
Step 4: Simplify the Lorentz transformation equation. Calculate the denominator, which involves the Lorentz factor: . This accounts for relativistic effects due to the high velocity (v = 0.88c).
Step 5: Compare the results from both transformations. The Galilean transformation assumes no relativistic effects, while the Lorentz transformation incorporates time dilation and length contraction. This comparison highlights the importance of using the correct transformation for high-speed scenarios.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Galilean Transformation
The Galilean transformation is a set of equations used to relate the coordinates of an event as observed in two different inertial reference frames that are moving at constant velocity relative to each other. It assumes that time is absolute and the same for all observers, leading to simple additive relationships between the coordinates. This transformation is valid at speeds much less than the speed of light.
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Lorentz Transformation
The Lorentz transformation is a set of equations that relate the space and time coordinates of events as observed in two inertial frames moving at a significant fraction of the speed of light. Unlike Galilean transformations, Lorentz transformations account for the effects of time dilation and length contraction, which become significant at relativistic speeds. This transformation is essential for understanding the behavior of objects moving close to the speed of light.
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Time Dilation
Time dilation is a phenomenon predicted by the theory of relativity, where time is measured to be moving slower for an observer in motion relative to a stationary observer. This effect becomes pronounced at speeds approaching the speed of light, leading to discrepancies in the measurement of time intervals. In the context of the problem, it is crucial to consider how time is perceived differently in the two reference frames when calculating the position of the object.
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