Question

an elevator of mass m = 400 kg starts from rest and is lowered to the ground by a rope in three stages. During the first second, it accelerates at 3 m/s^2 downward, then continues at a constant speed for six seconds, then slows down to a rest at 1 m/s^2 for three seconds.

a) find the initial height of the elevator.

b) find the total work done by the elevator by the rope.

c) find the average power done by the rope over each of the three stages.

Answer #1

A(n) 603 kg elevator starts from rest. It moves upward for 3.88
s with a constant acceleration until it reaches its cruising speed
of 1.78 m/s. The acceleration of gravity is 9.8 m/s 2 . Find the
average power delivered by the elevator motor during this period.
Answer in units of kW.

A 643-kg elevator starts from rest and moves upward for 3.80 s
with constant acceleration until it reaches its cruising speed,
1.69 m/s. (a) What is the average power of the elevator motor
during this period? . hp (b) How does this amount of power compare
with its power during an upward trip with constant speed? (Give the
power during an upward trip with constant speed.) hp

ELEVATORS A100 kg person is standing on a scale in an
elevator. Starting from rest, the elevator descent attaining a
downward speed of 2.0m/s in 4sec. it then travels with a constant
speed during the next 2 sec. finally the elevator undergoes a
uniform acceleration I. the positive y direction for 10 sec and
comes to rest g=9.8m/s^2
what is the scale reading
1. before the elevauor starts
2. during 1st accel
3,while constant
4. during the time slowing down

A car starts from rest at a stop sign. It accelerates at 2.0
m/s2 for 7.0 seconds, coasts For 2.7 s, and then slows down at a
rate of 1.5 m/s2 for the next stop sign. How far apart are the stop
signs?

The floor to ceiling height of an elevator is 4.5?.
The elevator starts from the ground at rest and accelerates
upward at 6?/?2. At ?=1?, a lamp on the elevator ceiling starts to
fall (due to high ?forces).
How long will it take the lamp to hit the floor? Solve this
problem in two ways:
a) From the perspective of a fixed X-Yframe(the ground
frame).
b) From the perspective of a frame moving with the elevator (the
relative frame).

A 1.50 ✕ 103-kg car starts from rest and accelerates
uniformly to 16.0 m/s in 12.9 s. Assume that air resistance remains
constant at 400 N during this time.
(a) Find the average power developed by the engine.
____ hp
(b) Find the instantaneous power output of the engine at t
= 12.9 s, just before the car stops accelerating.
______ hp

A 1.50 ✕ 103-kg car starts from rest and accelerates
uniformly to 15.1 m/s in 12.7 s. Assume that air resistance remains
constant at 400 N during this time.
(a) Find the average power developed by the engine. (hp)
(b) Find the instantaneous power output of the engine at t
= 12.7 s, just before the car stops accelerating. (hp)

An elevator filled with passengers has a mass of 1583 kg.
(a) The elevator accelerates upward from rest at a rate of 1.20
m/s2 for 2.00 s. Calculate the tension in the cable (in
N) supporting the elevator.
(b)The elevator continues upward at constant velocity for 9.22
s. What is the tension in the cable (in N) during this time?
(c)The elevator decelerates at a rate of 0.600 m/s2
for 4.00 s. What is the tension in the cable (in...

An elevator brimming with tourists has a mass of 1900 kg. The
elevator accelerates upward (in the positive direction) from rest
at a rate of 1.8 m/s2 for 2.5 s. The elevator continues
upward at constant velocity for 8.2 s. The elevator experiences a
negative acceleration at a rate of 0.45 m/s2 for 2.1
s.
How far, in meters, has the elevator moved above its original
starting point?

A car starts from rest at a stop sign. It accelerates at 3.6
m/s^2 for 6.5 s, coasts for 1.7 s, and then slows down at a rate of
2.5 m/s^2 for the next stop sign.
How far apart are the stop signs?

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