Question

Лифт разгоняется до скорости 7 м/с в течении 15 сек. Столько же времени занимает его возвращение в первоначальное положение. Найти вес человека поднявшегося вверх и опустившегося вниз если его вес равен 80 кг

Answer 1

Вес останется таким же. Он меняется толь при движении с ускорением.

Answer 2

#### Calculation of Time and Distance To find the time it takes for the elevator to return to its initial position, we can assume that the elevator moves at a constant speed of 7 m/s. Since the elevator takes 15 seconds to reach its maximum speed, we can assume that it also takes 15 seconds to decelerate and come to a stop. Therefore, the total time for the elevator to return to its initial position is 15 seconds for acceleration, 15 seconds for deceleration, and the time it takes to cover the distance traveled. Since the elevator is traveling at a constant speed of 7 m/s, we can calculate the distance traveled using the formula: **Distance = Speed × Time** The distance traveled during acceleration and deceleration is the same, as the elevator covers the same distance in both directions. Therefore, the total distance traveled is twice the distance traveled during acceleration or deceleration. Let's calculate the distance traveled during acceleration and deceleration: **Distance = Speed × Time = 7 m/s × 15 s = 105 meters** Since the elevator covers this distance twice (once during acceleration and once during deceleration), the total distance traveled is: **Total Distance = 2 × Distance = 2 × 105 meters = 210 meters** #### Calculation of Weight To calculate the weight of the person who went up and down in the elevator, we need to consider the force exerted on the person during the upward and downward motion. The force exerted on an object is equal to its weight, which is given by the formula: **Weight = Mass × Gravity** The mass of the person is given as 80 kg. The acceleration due to gravity is approximately 9.8 m/s^2. Let's calculate the weight of the person: **Weight = Mass × Gravity = 80 kg × 9.8 m/s^2 = 784 N** Therefore, the weight of the person who went up and down in the elevator is 784 Newtons. Please note that the calculations provided are based on the assumptions made and may not account for all real-world factors.