(II) High-speed elevators function under two limitations: (1) the maximum magnitude of vertical acceleration that a typical human body can experience without discomfort is about 1.2 m/s 2 , and (2) the typical maximum speed attainable is about 9.0 m/s. You board an elevator on a skyscraper’s ground floor and are transported 180 m above the ground level in three steps: acceleration of magnitude 1.2 m/s 2 from rest to 9.0 m/s, followed by constant upward velocity of 9.0 m/s, then deceleration of magnitude 1.2 m/s 2 from 9.0 m/s to rest. ( a ) Determine the elapsed time for each of these 3 stages. ( b ) Determine the change in the magnitude of the normal force, expressed as a % of your normal weight during each stage. ( c ) What fraction of the total transport time does the normal force not equal the person’s weight?
(II) High-speed elevators function under two limitations: (1) the maximum magnitude of vertical acceleration that a typical human body can experience without discomfort is about 1.2 m/s 2 , and (2) the typical maximum speed attainable is about 9.0 m/s. You board an elevator on a skyscraper’s ground floor and are transported 180 m above the ground level in three steps: acceleration of magnitude 1.2 m/s 2 from rest to 9.0 m/s, followed by constant upward velocity of 9.0 m/s, then deceleration of magnitude 1.2 m/s 2 from 9.0 m/s to rest. ( a ) Determine the elapsed time for each of these 3 stages. ( b ) Determine the change in the magnitude of the normal force, expressed as a % of your normal weight during each stage. ( c ) What fraction of the total transport time does the normal force not equal the person’s weight?
(II) High-speed elevators function under two limitations: (1) the maximum magnitude of vertical acceleration that a typical human body can experience without discomfort is about 1.2 m/s2, and (2) the typical maximum speed attainable is about 9.0 m/s. You board an elevator on a skyscraper’s ground floor and are transported 180 m above the ground level in three steps: acceleration of magnitude 1.2 m/s2 from rest to 9.0 m/s, followed by constant upward velocity of 9.0 m/s, then deceleration of magnitude 1.2 m/s2 from 9.0 m/s to rest. (a) Determine the elapsed time for each of these 3 stages. (b) Determine the change in the magnitude of the normal force, expressed as a % of your normal weight during each stage. (c) What fraction of the total transport time does the normal force not equal the person’s weight?
A car traveling at 35 m/s suddenly runs out of gas while driving
up a 7° incline. How long will it take for the car to stop after it
runs out of gas (if it doesn't use its brakes and there is no
friction)? How far will it travel before it stops?
A jet plane has a takeoff speed of Vto = 73 m/s and can move along the runway at an average acceleration of 1.5 m/s². If
the length of the runway is 1.7 km, will the plane be able to use this runway safely?
O Yes
No
Defend your answer.
A slanted roof rises at 35° above the horizontal, and the straight-line distance from the top of the roof to the bottom edge is 4.5 m. The roof is covered with ice, so it offers no friction to objects sliding on it. A piece of ice at the top suddenly breaks loose and begins to slide down from rest.(a) How long will it take for the ice to reach the bottom edge of the roof?(b) How fast will the ice be traveling just as it reaches the bottom edge?
Chapter 4 Solutions
Physics for Scientists and Engineers with Modern Physics
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