In a dramatic lecture demonstration, a physics professor blows hard across the top of a copper penny that is at rest on a level desk. By doing this at the right speed, he can get the penny to accelerate vertically, into the airstream, and then deflect it into a tray, as shown in Fig. 9.42. Assuming the diameter of a penny is 1.90 cm and its mass is 2.50 g, what is the minimum airspeed needed to lift the penny off the tabletop? Assume the air under the penny remains at rest.
Answer to relevant QuestionsThe spout heights in the container in Fig. 9.43 are 10 cm, 20 cm, 30 cm, and 40 cm. The water level is maintained at a 45-cm height by an outside supply. (a) What is the speed of the water out of each hole? (b) Which water ...The pulmonary artery, which connects the heart to the lungs, is about 8.0 cm long and has an inside diameter of 5.0 mm. If the flow rate in it is to be , what is the required pressure difference over its length? (a) Referring to the metal rod in Figure 9.2a (under tensile stress), show that Eq. 9.4 can be rewritten to resemble a Hooke’s law type of spring relationship for the rod. That is, show that it can be written as F = k ...A circular ring of iron has a tight- fitting iron bar across its diameter, as illustrated in Fig. 10.21. If the arrangement is heated in an oven to a high temperature, will the circular ring be distorted? What if the bar is ...Fig. 10.5 is a plot of Fahrenheit temperature versus Celsius temperature. (a) Is the value of the y-intercept found by setting (1) TF = TC, (2) TC = 0, or (3) TF = 0? Why? (b) Compute the value of the y-intercept. (c) ...
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