Each of the 4 engines on a Boeing 747 delivers about 30,000 horsepower at its cruising speed. If such a plane is cruising at 950 km/hr, powered by all 4 engines, what is the average force of thrust provided by the engines?
If a constant, nondissipative external force is applied to a solid block, and it is found that the rate at which energy is delivered by the force is constant as the block moves horizontally, the speed of the block will also be constant.
The motion of the block depicts a constant speed.
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Dolphins of the open ocean are classified as Type II Odontocetes (toothed whales). These animals use ultrasonic "clicks" with a frequency of 55 kHz to navigate and find prey. (a) Suppose a dolphin sends out a series of clicks that are reflected back from the bottom of the ocean 75 m below. How much time elapses before the dolphin hears the echoes of the clicks? (The speed of sound in seawater is approximately 1530 m/s.) (b) What is the wavelength of a 55-kHz sound in the ocean?
The minute and hour hands of a clock have a common axis of rotation and equal masses. The minute hand is long, thin, and uniform; the hour hand is short, thick, and uniform. (a) Is the moment of inertia of the minute hand greater than, less than, or equal to the moment of inertia of the hour hand? (b) Choose the best explanation from among the following: A. The hands have equal masses, and hence equal moments of inertia. B. Having mass farther from the axis of rotation results in a greater moment of inertia. C. The more compact hour hand has its mass more concentrated and thus has the greater moment of inertia.