I think it might be A. I’m sorry if I’m wrong
1.Density of the material building the raft must be lower than the water.
<span>2. Material must not react with water. </span>
<span>3.Material must have high strength. </span>
<span>4.Raft must be wide in-order to avoid drawing in the river.</span>
Answer:
VR = 
Explanation:
A machine is a device that can be used to overcome a load by the application of an effort through a pivot. Examples are: pulleys, wedge, screw jack, wheel and axle etc.
The wheel and axle is a simple device that can be used to lift a load through a height. Its velocity ratio (VR) can be determined by:
VR = 
Note that for a practical wheel and axle, the radius of the wheel is greater than the radius of the axle.
La longitud <em>final</em> del puente de acero es 100.018 metros.
Asumamos que la dilatación <em>térmica</em> experimentada por el puente de acero es <em>pequeña</em>, de modo que podemos emplear la siguiente aproximación <em>lineal</em> para determinar la longitud <em>final</em> del puente de acero (
), en metros:
(1)
Donde:
- Longitud inicial del puente, en metros.
- Coeficiente de dilatación, sin unidad.
- Temperatura inicial, en grados Celsius.
- Temperatura final, en grados Celsius.
Si tenemos que
,
,
y
, entonces la longitud final del puente de acero es:
![L = (100\,m)\cdot [1+(11.5\times 10^{-6})\cdot (24\,^{\circ}C - 8\,^{\circ}C)]](https://tex.z-dn.net/?f=L%20%3D%20%28100%5C%2Cm%29%5Ccdot%20%5B1%2B%2811.5%5Ctimes%2010%5E%7B-6%7D%29%5Ccdot%20%2824%5C%2C%5E%7B%5Ccirc%7DC%20-%208%5C%2C%5E%7B%5Ccirc%7DC%29%5D)

La longitud <em>final</em> del puente de acero es 100.018 metros.
Para aprender más sobre dilatación térmica, invitamos cordialmente a ver esta pregunta verificada: brainly.com/question/24953416
If u mean pressure, pressure = Force/Area
Correct me if I am wrong :D