Ask question

Ask question

All categories

2 years ago

12

7. Two children of mass 20 kg and 30 kg sit balanced on a seesaw with the pivot point located at the center of the seesaw. If th

e children are separated by a distance of 3 m, at what distance from the pivot point is the small child sitting in order to maintain the balance?

1 answer:

Ainat [17]2 years ago

7 0

Answer:

Explanation:

Given

mass of children $m_1=20\ kg$

$m_2=30\ kg$

distance between two children $L=3\ m$

suppose small child is at a distance of x m from pivot point

so torque of small child and heavier child must be equal

$20\times (x)=30\times (3-x)$

$2x=9-3x$

$5x=9$

$x=1.8\ m$

You might be interested in

Steam flows steadily through an adiabatic turbine. The inlet conditions of the steam are 4 MPa, 500°C, and 80 m/s and the exit c

FrozenT [24]

Answer:

a) $\Delta \dot K = 24.570\,kW$ , b) $\dot W_{out} = 12729.15\,kW$ , c) $A_{in} = 0.0136\,m^{2}$

Explanation:

A turbine is a device which works usually in steady state and assumption of being adiabatic means no heat interactions between steam through turbine and surroudings and produce mechanical work from fluid energy. Changes in gravitational energy can be neglected. This system can be modelled after the First Law of Thermodynamics:

$-\dot W_{out} + \dot m \cdot (h_{in} - h_{out}) + \frac{1}{2}\cdot \dot m \cdot (v_{in}^{2}-v_{out}^{2}) = 0$

a) Change in kinetic energy

$\Delta \dot K = \frac{1}{2}\cdot \dot m \cdot (v_{in}^{2} - v_{out}^{2})$

$\Delta \dot K = \frac{1}{2} \cdot \left(12.6\,\frac{kg}{s} \right) \cdot \left[\left(80\,\frac{m}{s} \right)^{2}-\left(50\,\frac{m}{s} \right)^{2}\right]$

$\Delta \dot K = 24570\,W$

$\Delta \dot K = 24.570\,kW$

b) Power output

$\dot W_{out} = \dot m \cdot (h_{in} - h_{out}) + \frac{1}{2}\cdot \dot m \cdot (v_{in}^{2}-v_{out}^{2})$

$\dot W_{out} = \left(12.6\,\frac{kg}{s}\right)\cdot \left(3446\,\frac{kJ}{kg} - 2437.7\,\frac{kJ}{kg} \right) + 24.570\,kW$

$\dot W_{out} = 12729.15\,kW$

c) Turbine inlet area

Turbine inlet area can be found by using the following expressions:

$\dot V_{in} = \dot m \cdot \nu_{in}$

$\dot V_{in} = \left(12.6\,\frac{kg}{s}\right) \cdot \left(0.086442\,\frac{m^{3}}{kg} \right)$

$\dot V_{in} = 1.089\,\frac{m^{3}}{s}$

$A_{in} = \frac{\dot V_{in}}{v_{in}}$

$A_{in} = \frac{1.089\,\frac{m^{3}}{s} }{80\,\frac{m}{s} }$

$A_{in} = 0.0136\,m^{2}$

8 0

2 years ago

What is meant by a quantity ? Mention any three system of unit that you know to measure a

d1i1m1o1n [39]

<em> </em>

<em> the quantity which can be measured is called </em>

<em> the quantity which can be measured is called quantity for example length and mass time temperature </em>

<em> the quantity which can be measured is called quantity for example length and mass time temperature please brainlist </em>

<em> the quantity which can be measured is called quantity for example length and mass time temperature please brainlist </em>

4 0

2 years ago

Plz help a smol bean out (no links btw)

Marina86 [1]

Hey! If this is on big ideas get a app called “Slader” It has answers to all math problems just like up the book you use > save it > type in the section you are doing > and look for the problems you are doing.

8 0

2 years ago

The law of conservation of matter states that matter can be neither created nor destroyed. Your friend shows you the following c

MrRa [10]

Yes, our friend is right, because there is no contradiction to the law of conservation of mass in the above equation. It just the mass of the product is equal to the mass of reactants.. and that is shown in the equation you have presented earlier

7 0

2 years ago

Garret's swimming coach is giving him important and helpful tips to improve his swimming skills. Which gesture suggests that Gar

bogdanovich [222]

Answer: "important and helpful" Show garret is paying close attention to her coach. Hope this help!

7 0

2 years ago

Read 2 more answers