Bam!— Apollo 15 Lands on the Moon The first word spoken on the surface of the Moon after Apollo 15 landed on July 30, 1971, was “Bam!” This was James Irwin’s involuntary reaction to their rather bone-jarring touchdown. “We did hit harder than any of the other flights!” says Irwin. “And I was startled, obviously, when I said. Bam!’" The reason for the “firm touchdown” of Apollo 15, as pilot David Scott later characterized it, was that the rocket engine was shut off a bit earlier than planned, when the lander was still 4.30 ft above the lunar surface and moving downward with a speed of 0.500 ft/s. From that point on the lander descended in lunar free fall, with an acceleration of 1.62 m/s 2 . As a result, the landing speed of Apollo 15 was by far the largest of any of the Apollo missions In comparison, Neil Armstrong s landing speed on Apollo 11 was the lowest at 1.7 ft/s—he didn’t shut off the engine until the footpads were actually on the surface. Apollos 12 , 14 , and 17 all landed with speeds between 3.0 and 3.5 ft/s. To better understand the descent of Apollo 15, we show its trajectory during the final stages of landing in Figure 2-47 (a) In Figure 2-47 (b) we show a variety of speed-versus-time plots. (a) (b) FIGURE 2-4 7 Problems 108, 109, 110, and 111 110. • Which of the speed-versus-time plots in Figure 2-48 (b) correctly represents the speed of the Apollo 15 lander? A B C D
Bam!— Apollo 15 Lands on the Moon The first word spoken on the surface of the Moon after Apollo 15 landed on July 30, 1971, was “Bam!” This was James Irwin’s involuntary reaction to their rather bone-jarring touchdown. “We did hit harder than any of the other flights!” says Irwin. “And I was startled, obviously, when I said. Bam!’" The reason for the “firm touchdown” of Apollo 15, as pilot David Scott later characterized it, was that the rocket engine was shut off a bit earlier than planned, when the lander was still 4.30 ft above the lunar surface and moving downward with a speed of 0.500 ft/s. From that point on the lander descended in lunar free fall, with an acceleration of 1.62 m/s 2 . As a result, the landing speed of Apollo 15 was by far the largest of any of the Apollo missions In comparison, Neil Armstrong s landing speed on Apollo 11 was the lowest at 1.7 ft/s—he didn’t shut off the engine until the footpads were actually on the surface. Apollos 12 , 14 , and 17 all landed with speeds between 3.0 and 3.5 ft/s. To better understand the descent of Apollo 15, we show its trajectory during the final stages of landing in Figure 2-47 (a) In Figure 2-47 (b) we show a variety of speed-versus-time plots. (a) (b) FIGURE 2-4 7 Problems 108, 109, 110, and 111 110. • Which of the speed-versus-time plots in Figure 2-48 (b) correctly represents the speed of the Apollo 15 lander? A B C D
The first word spoken on the surface of the Moon after Apollo 15 landed on July 30, 1971, was “Bam!” This was James Irwin’s involuntary reaction to their rather bone-jarring touchdown. “We did hit harder than any of the other flights!” says Irwin. “And I was startled, obviously, when I said. Bam!’"
The reason for the “firm touchdown” of Apollo 15, as pilot David Scott later characterized it, was that the rocket engine was shut off a bit earlier than planned, when the lander was still 4.30 ft above the lunar surface and moving downward with a speed of 0.500 ft/s. From that point on the lander descended in lunar free fall, with an acceleration of 1.62 m/s2. As a result, the landing speed of Apollo 15 was by far the largest of any of the Apollo missions In comparison, Neil Armstrong s landing speed on Apollo 11 was the lowest at 1.7 ft/s—he didn’t shut off the engine until the footpads were actually on the surface. Apollos 12, 14, and 17 all landed with speeds between 3.0 and 3.5 ft/s.
To better understand the descent of Apollo 15, we show its trajectory during the final stages of landing in Figure 2-47 (a) In Figure 2-47 (b) we show a variety of speed-versus-time plots.
(a)
(b)
FIGURE 2-47
Problems 108, 109, 110, and 111
110. • Which of the speed-versus-time plots in Figure 2-48 (b) correctly represents the speed of the Apollo 15 lander?
In 2004 two Martian probes successfully landed on the Red Planet. The final phase of the landing involved bouncing the probes until they came to rest (they were surrounded by protective inflated “balloons”). During one of the bounces, the telemetry (electronic data sent back to Earth) indicated that the probe too off at 25.0 m/s at an angle of 20 degrees and landed 110 m away (and then bounced again). Assuming the landing region was level, determine the acceleration due to gravity near the Martian surface.
Suppose you are an intrepid interplanetary explorer and you've landed on the remote planet, Gorzag. Your task is to determine the free-fall acceleration on the surface of Gorzag, which has no atmosphere. All you have is a space rock, a stop watch, and a laser range finder (a tool to measure distance). You find a nearby cliff and make the following measurements: the height of the cliff is 55m, and when you drop the rock off the cliff it takes 40s for the rock to hit the ground below. Show your work.
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ou are riding a galloping horse around a circular track at a constant speed. Does the horse's velocity change? Briefly explain why or why not.
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