A 100%-efficient engine is being used to raise a 89-kg crate vertically upward at a steady rate. If the power output of the engine is 1620 W,
how long does it take the engine to lift the crate a vertical distance of 18.7 m? Friction in the system is negligible.
10 s
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Rotational Kinetic Energy: A solid uniform ball with a mass of 125 g is rolling without slipping along the horizontal surface of a table with a speed of 4.5 m/s when it rolls off the edge and falls towards the floor, 1.1 m below. What is the rotational kinetic energy of the ball just before it hits the floor?
A. 0.51 J B. 0.73 J C. 1.1 J D. 2.6 J E. This question cannot be answered without knowing the radius of the ball.
A nitrogen molecule has a diameter of about 0.29 nm. The mean free path of a nitrogen molecule in a tank of dry nitrogen at room temperature and standard pressure is about 0.10 ?m. A tank containing nitrogen at standard temperature and pressure has volume V. If the tank is compressed by means of a piston to 20% of its original volume, what is the mean free path for a nitrogen molecule under the new conditions?
A. 0.089 ?m B. 0.125 ?m C. 0.080 ?m D. 0.112 ?m
The process of photosynthesis is important because it
A) converts carbon and water to hydrocarbon and free oxygen. B) contributed to the development of an ozone layer. C) is an energy source that drives the geologic process. D) allowed increased infiltration of solar energy.
A 320-g air track cart traveling at 1.25 m/s collides elastically with a stationary 270-g cart. What is the speed of the 270-g cart after the collision?
A) 0.678 m/s B) 0.106 m/s C) 1.36 m/s D) 1.14 m/s E) 2.72 m/s