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题目

多项选择题

Question at position 3 Which of the following statements are true regarding the equations in the introduction of the lab worksheet? Select all statements that are true. Equation 7.7 assumes the pendulum's speed at the top of its motion is maximum.Equation 7.7 assumes that external nonconservative forces, such as air drag or the friction between the pendulum and the pivot point, do no work on the pendulum-ball system when the pendulum swings upwards. Equation 7.7 assumes only conservative forces act on the ball during its collision with the pendulum's catcher.Equation 7.7 assumes the pendulum has negligible mass.Equation 7.7 assumes the ball bounces off the pendulum's catcher, so both move in opposite directions immediately after the collision.Equation 7.17 assumes that only one force acts on the ball when it's in the air.Equation 7.17 assumes the ball's acceleration is constant when it's in the air.Equation 7.17 assumes the ball travels a horizontal distance RR after falling a vertical distance HH.None of the above statements are true.

选项

A.Equation 7.7 assumes the pendulum's speed at the top of its motion is maximum.

B.Equation 7.7 assumes that external nonconservative forces, such as air drag or the friction between the pendulum and the pivot point, do no work on the pendulum-ball system when the pendulum swings upwards.

C.Equation 7.7 assumes only conservative forces act on the ball during its collision with the pendulum's catcher.

D.Equation 7.7 assumes the pendulum has negligible mass.

E.Equation 7.7 assumes the ball bounces off the pendulum's catcher, so both move in opposite directions immediately after the collision.

F.Equation 7.17 assumes that only one force acts on the ball when it's in the air.

G.Equation 7.17 assumes the ball's acceleration is constant when it's in the air.

H.Equation 7.17 assumes the ball travels a horizontal distance 𝑅 after falling a vertical distance 𝐻 .

I.None of the above statements are true.

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标准答案

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思路分析

The question asks which statements about Equation 7.7 and Equation 7.17 are true, given the lab worksheet context. We'll evaluate each option in turn, noting why it could be correct or incorrect based on typical pendulum-ball collision and projectile-motion assumptions. Option 1: 'Equation 7.7 assumes the pendulum's speed at the top of its motion is maximum.' This would be inconsistent with a simple pendulum under energy conservation, where the speed is zero at the top (instantaneous reversal point) and maximum at the bottom of the swing. Therefore, this statement is false because the top speed is not maximum. Option 2: 'Equation 7.7 assumes that external nonconservative forces, such as air drag or the friction between the pendulum and the pivot point, do no work on the pendulum-ball system when the pendulum swings upwards.' This aligns ......Login to view full explanation