Question

Q8: (10 점, 부교재 9 장 34 번, 수업시간에 소개한 도마뱀 얘기입니다) Basilisk lizards can run across the top of a water surface. With each step, a lizard first slaps its foot against the water and then pushes it down into the water rapidly enough to form an air cavity around the top of the foot. To avoid having to pull the foot back up against water drag in order to complete the step, the lizard withdraws the foot before water can flow into the air cavity. If the lizard is not to sink, the average upward impulse on the lizard during this full action of slap, downward push, and withdrawal must match the downward impulse due to the gravitational force. Suppose the mass of a basilisk lizard is 90.0 g, the mass of each foot is 3.00 g, the speed of a foot as it slaps the water is 1.50 m/s, and the time for a single step is 0.600 s. (a) What is the magnitude of the impulse on the lizard during the slap? (Assume this impulse is directly upward.) (b) During the 0.600 s duration of a step, what is the downward impulse on the lizard due to the gravitational force? (c) Which action, the slap or the push, provides the primary support for the lizard, or are they approximately equal in their support? Q9: (10 점 부교재 9 장 69 번) A small ball of mass m is aligned above a larger ball of mass M-0.630 kg (with a slight separation between two balls), and the two balls are dropped simultaneously from a height of 1.80 m. (Assume the radius of each ba is negligible relative to h.) (a) If the larger ball rebounds elastically from the floor and then the small ball rebounds elastically from the larger ball, what value of m results in the larger bal stopping when it collides with the small ball? (b) What height does the small ball then reach?

Answer 1

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