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Paraphin [41]
2 years ago
12

3. (9 points) A square-thread power screw is used to raise or lower the basketball board in a gym, the weight of which is W = 10

0kg. See the following two figures. For power screws, assume a major diameter d = 20mm, and a pitch of p = 2mm with double threads. The friction coefficient of steel parts is f = 0.1. Gravity constant is g = 10????/kg. (a) (7 points) If the purchased Cordless Electric Power Screwdrivers rotates at 300rpm, determine the power you need to raise to the basket board. (b) (2 points) Check if the self-locking condition of the power screw is satisfied or not.
Engineering
1 answer:
Bezzdna [24]2 years ago
3 0

Answer:

a) 49.95 watts

b) The self locking condition is satisfied

Explanation:

Given data

weight of the square-thread power screw ( w ) = 100 kg = 1000 N

diameter (d) = 20 mm ,

pitch (p) = 2 mm

friction coefficient of steel parts ( f ) = 0.1

Gravity constant ( g ) = 10 N/kg

Rotation of electric power screwdrivers = 300 rpm

A ) Determine the power needed to raise to the basket board

first we have to calculate T

T = Wtan (∝ + Ф ) * \frac{Dm}{2} ------------- equation 1

Dm = d - 0.5 ( 2) = 19mm

Tan ∝ = \frac{L}{\pi  Dm}  where L = 2*2 = 4

hence ∝ = 3.83⁰

given f = 0.1 , Tan Ф = 0.1.     hence Ф = 5.71⁰

insert all the values into equation 1

T = 1.59 Nm

Determine the power needed using this equation

\frac{2\pi NT }{60}   =  \frac{2\pi * 300 * 1.59}{60}

= 49.95 watts

B) checking if the self-locking condition of the power screw is satisfied

Ф > ∝  hence it is self locking condition is satisfied

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A gas flows through a one-inlet, one-exit control volume operating at steady state. Considering an adiabatic control volume with
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Answer:

b. equal to the specific entropy of the gas at the inlet.

Explanation:

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If a process is completely reversible, without the need to provide energy in the form of heat, then the process is isentropic.

3 0
3 years ago
In using the drag coefficient care needs to be taken to use the correct area when determining the drag force. What is a typical
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Explanation:

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  F_D=\dfrac{1}{2}C_D\rho AV^2

Where

             C_D is the drag force constant.

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                V is the velocity.

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6 0
3 years ago
A labor-intensive process to manufacture a product has a fixed cost of $338,000 and a variable cost of $143 per unit. An automat
ozzi

Answer:

no of unit is 17941

Explanation:

given data

fixed cost = $338,000

variable cost = $143 per unit

fixed cost = $1,244,000  

variable cost = $92.50 per unit

solution

we consider here no of unit is = n

so here total cost of labor will be sum of fix and variable cost i.e

total cost of labor = $33800 + $143 n  ..........1

and

total cost of capital intensive  = $1,244,000 + $92.5 n   ..........2

so here in both we prefer cost of capital if cost of capital intensive less than cost of labor

$1,244,000 + $92.5 n  <  $33800 + $143 n

solve we get

n > \frac{906000}{50.5}

n > 17941

and

cost of producing less than selling cost so here

$1,244,000 + $92.5 n < 197 n

solve it we get

n > \frac{1244000}{104.5}  

n > 11904

so in both we get greatest no is 17941

so no of unit is 17941

3 0
3 years ago
Calculate the volume of a hydraulic accumulator capable of delivering 5 liters of oil between 180 and 80 bar, using as a preload
Vinil7 [7]

Answer:

1) V_o = 10 liters

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For isothermal process n =1

V_o =\frac{\Delta V}{(\frac{p_o}{p_1})^{1/n} -(\frac{p_o}{p_2})^{1/n}}

V_o  = \frac{5}{[\frac{72}{80}]^{1/1} -[\frac{72}{180}]^{1/1}}

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correction factor for calculate dpressure ration  for isothermal process is

c1 = 1.03

actual \ volume = c1\times 10 = 10.3 liters

b) for adiabatic process

n =1.4

volume of hydraulic accumulator is given as

V_o =\frac{\Delta V}{[\frac{p_o}{p_1}]^{1/n} -[\frac{p_o}{p_2}]^{1/n}}

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V_o = 12.26 liters

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correction factor for calculate dpressure ration  for isothermal process is

c1 = 1.15

actual \volume = c1\times 10 = 11.5 liters

8 0
3 years ago
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