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The effects of gravity are effectively negated if an object is in free fall. For example, an object orbiting the Earth experiences an apparent weightlessness known as microgravity. Because the human body evolved under the influence of Earth's gravity, human physiology undergoes several changes in microgravity environments. Puffy face syndrome (PFS) occurs when an astronaut's extracellular fluid shifts toward upper body regions, resulting in facial bulging and leg shrinkage. Elongation of the spinal column also occurs as intervertebral discs (spinal cartilage) decompress, making astronauts up to 6 cm taller.Researchers simulated microgravity-induced spinal elongation on Earth by suspending 50 volunteers by the arms, holding each above the ground in an upright position. The thickness of each intervertebral disc was measured prior to and following 10 minutes of suspension. Researchers then compared the percentage change in intervertebral disc thickness to similar measurements recorded in microgravity, as shown in Figure 1.
Figure 1 Percentage change in intervertebral disc thicknessIn theory, spinal elongation would also occur in reduced-gravity environments like the surface of the Moon, where the acceleration of gravity is one-sixth that observed on the Earth's surface.
-Provided that the initial velocity in both circumstances is identical, how much longer will an astronaut's vertical jumps last on the surface of the Moon compared to on the surface of the Earth?

Question

Passage
The effects of gravity are effectively negated if an object is in free fall. For example, an object orbiting the Earth experiences an apparent weightlessness known as microgravity. Because the human body evolved under the influence of Earth's gravity, human physiology undergoes several changes in microgravity environments. Puffy face syndrome (PFS) occurs when an astronaut's extracellular fluid shifts toward upper body regions, resulting in facial bulging and leg shrinkage. Elongation of the spinal column also occurs as intervertebral discs (spinal cartilage) decompress, making astronauts up to 6 cm taller.Researchers simulated microgravity-induced spinal elongation on Earth by suspending 50 volunteers by the arms, holding each above the ground in an upright position. The thickness of each intervertebral disc was measured prior to and following 10 minutes of suspension. Researchers then compared the percentage change in intervertebral disc thickness to similar measurements recorded in microgravity, as shown in Figure 1.

Figure 1 Percentage change in intervertebral disc thicknessIn theory, spinal elongation would also occur in reduced-gravity environments like the surface of the Moon, where the acceleration of gravity is one-sixth that observed on the Earth's surface.
-Provided that the initial velocity in both circumstances is identical, how much longer will an astronaut's vertical jumps last on the surface of the Moon compared to on the surface of the Earth?

Quizplus · Accepted Answer

11ecba2d_12dd_24be_a3bf_8d9f6068dbf4_MD0008_00 The time of flight for projectiles can be determined from translation motion equations. Specifically, the linear position x of an object with constant acceleration a is given by the kinematic equation: 11ecba2d_12dd_24bf_a3bf_cf6e34bd4188_MD0008_00 In the case of vertical motion (y-axis), the acceleration of gravity g points downward and is therefore negative: 11ecba2d_12dd_24c0_a3bf_d9a5352ed56b_MD0008_00 When an astronaut completes a vertical jump, the difference between the final and initial position (y − y₀) is 0: 11ecba2d_12dd_24c1_a3bf_a1893f23cb95_MD0008_00 11ecba2d_12dd_24c2_a3bf_1929c6609372_MD0008_00 The equation above has two solutions when rearranged to solve for time t, the first of which is t = 0 (corresponding to the beginning of the jump). The second solution is: 11ecba2d_12dd_24c3_a3bf_8f36f9be1538_MD0008_00 where t corresponds to the end of the jump. Of note, the time of flight is inversely proportional to the acceleration of gravity g. Modifying the above equation to account for the significantly reduced gravity on the Moon (g_Moon) yields: 11ecba2d_12dd_4bd4_a3bf_8d644c8a4f4c_MD0008_00 Therefore, an object launched vertically from the surface of the Moon would take 6 times longer to return than an object launched vertically from the surface of the Earth (Choice D). Educational objective: Translational motion equations can be used to determine the height and travel of a projectile, the latter of which is inversely proportional to the acceleration of gravity.

Passage The Effects of Gravity Are Effectively Negated If an Object