Agroup of students is making model cars that will be propelled by model rocket engines. these engines provide a nearly constant thrust force. the cars are light—most of the weight comes from the rocket engine—and friction and drag are very small. as the engine fires, it uses fuel, so it is much lighter at the end of the run than at the start. a student ignites the engine in a car, and the car accelerates. as the fuel burns and the car continues to speed up, the magnitude of the acceleration willa. increaseb. stay the samec. decrease

Aleaky 10-kg bucket is lifted from the ground to a height of 15 m at a constant speed with a rope that weighs 0.7 kg/m. initially the bucket contains 45 kg of water, but the water leaks at a constant rate and finishes draining just as the bucket reaches the 15-m level. find the work done. (use 9.8 m/s2 for g.) show how to approximate the required work by a riemann sum. (let x be the height in meters above the ground. enter xi* as xi.) lim n → ∞ n (9.8)(45−3 xi) i = 1 δx express the work as an integral. 0 dx evaluate the integral. (round your answer to the nearest integer.) j