Question

Скоростной лифт разгоняется до скорости 8 м/с в течении 4 секунд. Какой вес человека массой 70 кг в начале движения лифта?

Answer 1

Дано t=4 с   V=8 м/с   m=70 кг   P- ?

так как ускорение направлено вверх ( хотя условие корявое) можно разгоняться и вниз

P = m*g+m*a
a=V/t=8/4=2 м/с2
P=70*(10+2)=840 Н

Answer 2

Calculation of Weight in the Elevator

To calculate the weight of a person in the elevator, we need to consider the acceleration and the force acting on the person.

Given: - Initial velocity (u) = 0 m/s (since the person is at rest at the beginning) - Final velocity (v) = 8 m/s - Time taken (t) = 4 seconds - Mass of the person (m) = 70 kg

We can use the equation of motion to calculate the acceleration (a) of the elevator:

v = u + at

Since the initial velocity (u) is 0, the equation simplifies to:

v = at

Rearranging the equation, we can solve for acceleration:

a = v / t

Substituting the given values:

a = 8 m/s / 4 s = 2 m/s^2

Now, we can calculate the force (F) acting on the person using Newton's second law of motion:

F = ma

Substituting the values:

F = 70 kg * 2 m/s^2 = 140 N

The weight of the person is equal to the force acting on them due to gravity. Therefore, the weight of the person in the elevator at the beginning of the motion is 140 N.