1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
MrMuchimi
3 years ago
5

An elevator motor provides 45.0 kW of power while lifting an elevator 35.0 m. If the elevator contains seven passengers each wit

h an average mass of 70.0 kg and it takes 20.0 s to accomplish this task, determine the mass of the elevator.
Physics
1 answer:
mylen [45]3 years ago
4 0

Find how much work ∆<em>W</em> is done by the motor in lifting the elevator:

<em>P</em> = ∆<em>W</em> / ∆<em>t</em>

where

• <em>P</em> = 45.0 kW = power provided by the motor

• ∆<em>W</em> = work done

• ∆<em>t</em> = 20.0 s = duration of time

Solve for ∆<em>W</em> :

∆<em>W</em> = <em>P</em> ∆<em>t</em> = (45.0 kW) (20.0 s) = 900 kJ

In other words, it requires 900 kJ of energy to lift the elevator and its passengers. The combined mass of the system is <em>M</em> = (<em>m</em> + 490.0) kg, where <em>m</em> is the mass of the elevator alone. Then

∆<em>W</em> = <em>M</em> <em>g h</em>

where

• <em>g</em> = 9.80 m/s² = acceleration due to gravity

• <em>h</em> = 35.0 m = distance covered by the elevator

Solve for <em>M</em>, then for <em>m</em> :

<em>M</em> = ∆<em>W</em> / (<em>g h</em>) = (900 kJ) / ((9.80 m/s²) (35.0 m)) ≈ 2623.91 kg

<em>m</em> = <em>M</em> - 490.0 kg ≈ 2133.91 kg ≈ 2130 kg

You might be interested in
A plane travels down a runway 2750 m before it lifts off at an angle of 37 degrees from the horizontal. The plane has traveled 1
ss7ja [257]

Answer: 4.236km

Explanation:

Let's define the point (x, y) as:

x = horizontal distance moved.

y = vertical distance moved.

If the plane starts in the point (0, 0) then:

"A plane travels down a runway 2750 m before it lifts off..."

At this time, the position will be:

P = (0 + 2750m, 0) = (2750m, 0).

"it lifts off at an angle of 37 degrees from the horizontal. The plane has traveled 1.8 km since its wheels left the ground."

In this case, as the angle is measured from the horizontal, the components will be:

x = 1.8km*cos(37°) = 1.438km

y = 1.8km*sin(37°) =  1.083 km

Then the new position is:

P = (2750m + 1.438 km, 0 + 1.083 km)

Let's write it using the same units for all the quantities:

we know that

1km = 1000m

Then:

2750m = (2750/1000) km = 2.750 km.

Then we can write the new position as:

P = (2.750 km + 1.438km, 1.083km) = (4.188km, 1.083km)

Now, we define the displacement as the distance between the final position and the initial position.

The distance between two points (a, b) and (c, d) is:

D = √( (a  c)^2 + (b - d)^2)

In this case the points are:

(0, 0) for the initial position

(4.188km, 1.083km) for the final position.

And the displacement will be:

D = √( (4.188km - 0)^2 + (1.083 - 0)^2) = 4.236km

5 0
3 years ago
Which part of an atom has most of its mass? A. electrons B. neutrons C. nucleus D. protons
vredina [299]

<em>The </em><em>nucleus</em><em> has most of the atomic mass in an atom. The </em><em>nucleus</em><em> is made up of protons and neutrons.</em>

<em />

6 0
3 years ago
Read 2 more answers
Which way do the players on the court rotate during a game? What happens if the players serve out of order?
tigry1 [53]

Answer:

Explanation:

on volleyballit's clockwise and What Would Happen If Someone Served Out Of Order? If the wrong player on your team serves because it's not their turn, the point and the possession of the serve will go to your opponents.

5 0
3 years ago
How many times can energy be transformed?
kykrilka [37]
Only once hope this helps
7 0
3 years ago
Read 2 more answers
If a crane worker lifts a crate with a mass of 250 kg from the ground to a
mina [271]

D.

The gravitational of a body is possessed by the body due to the virtue of its position.

The formula for gravitational potential energy is,

                                P.E = mgh joules

Substituting the values

196*9.8*250= 49k

7 0
2 years ago
Other questions:
  • Match the example to the type of equipment category it fits best in.
    14·1 answer
  • As you increase the number of supporting strings, what happens to the force needed to lift the bottom block
    11·1 answer
  • An 68 kg man on ice skates is pushing his 34 kg son, also on skates, with a force of 115 N. Together, they move across the ice s
    5·1 answer
  • How is circular motion different from variable motion?
    9·1 answer
  • What are the signs of "Depression"?
    12·2 answers
  • Describe the rise and fall of a basketball using the concepts of kinetic energy and potential energy
    14·1 answer
  • Suppose that there are N=108 two-state systems, each with energy difference E=6 × 10-21 J between the two states. The environmen
    12·1 answer
  • Two objects of the same mass move along the same line in opposite directions. The first mass is moving with speed . The objects
    12·1 answer
  • How does the mass of an object affect the outcome when an unbalanced force acts on it?
    14·1 answer
  • How to find angular velocity from linear velocity and radius.
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!