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Name ______________________________Date____________________ Chapter 7 Problem B 1. If you placed a helicopter with a mass of 1.03 103 kg on a large piston of a hydraulic lift, what force would need to be applied to the small piston in order to slowly lift the helicopter? Assume that the weight of the helicopter is distributed evenly over the large piston’s area, which is 1.40 102 m2. The area of the small piston is 0.80 m2. 2. Imagine an agricultural show in which a large goat with a mass of 181 kg exerts a pressure on a hydraulic-lift piston that is equal to the pressure exerted by three pygmy goats, each of which has a mass of 16.0 kg. The area of the piston on which the large goat stands is 1.8 m2. What is the area of the piston on which the pygmy goats stand? 3. The greatest load ever raised had a mass of 4.0 107 kg. Imagine that this load could have been raised using a single huge hydraulic lift. If the load had been placed on the large piston and a force of 1.2 104 N had been applied to the small piston, which had an area of 5.0 m2, what must the large piston’s area have been? 4. Suppose a pressure equal to that estimated for the sun’s interior (2.0 1016 Pa) acts on a spherical surface within a star. If a force of 1.02 N 1031 N produces this pressure, what is the area of the surface? What is the sphere’s radius r? (Recall that a sphere’s surface area equals 4r2.) 5. The surface of the planet Jupiter is believed to consist of liquid hydrogen. Above this surface lies a thick atmosphere that exerts a pressure of 1.00 x 107 Pa on Jupiter’s surface. If the total force exerted by this atmosphere is 6.41x1023 N, what is the area of Jupiter’s surface? 6. In a certain gasoline engine, the ignited gasoline and air mixture in a single cylinder exert a pressure of 1.50 x 106 Pa on the upper surface of the piston. If the force exerted by the gas on the piston is 1.22 x 104 N, how large is the area on the piston’s upper surface? 7. The two Echo satellites, which were launched in 1960 and 1964, were early examples of communications satellites. Suppose the gas pressure inside Echo 1 was the same as the atmospheric pressure at Earth’s surface. If the total force exerted on the inner surface of Echo 1 was 2.86 x 108 N, what was the surface area of the satellite? Given that the surface area of a sphere is 4πr2, what was the radius of the satellite? 8. A ball strikes the pavement with a force of 5.0 N. If the pressure exerted on the pavement is 9.6 x 103 Pa, what is the area of contact between the ball and the pavement? 9. A neutron star is a remnant of a massive star that has undergone an explosion called supernova. Suppose a neutron star is spherical with a radius of 6.0 km, its surface consists of closely packed neutrons, and the pressure beneath the surface layer of neutrons is 1.2 x 1016 Pa. If the surface area of a sphere is 4πr2, what force is exerted by the neutrons?