Answer:
21544 N
Explanation:
Let the atmospheric pressure be 101325 Pa
The side length of the cubic box:
The area of the cubic box:
20 C = 20 + 273 = 293 K
180 C = 180 + 273 = 453 K
As the volume of the air inside the closed cube is not changed, assume the ideal gas law we have
Where P1 = 101325 Pa and T1 = 293K are the original atmospheric pressure and temperature. P2 and T2 = 453 are the new pressure and temperature after the cube gets heat up
The net force on each side of the box it its pressure times side area
Answer:
Therefore maximum stretch is y2 = 32.36 m
Explanation:
In this problem let's use the initial data to find the string constant, let's apply Newton's second law when in equilibrium
- W = 0
k Δx = mg
k = mg / Δx
k = 80 9.8 / (30-20)
k = 78.4 N / m
now let's use conservation of energy to find the velocity of the body just as the string starts to stretch y = 20 m
starting point. When will you jump
Em₀ = U = mg y
final point. Just when the rope starts to stretch
= K = ½ m v²
Em₀ = Em_{f}
mg y = ½ m v²
v = √ 2g y
v = √ (2 9.8 20)
v = 19.8 m / s
now all kinetic energy is transformed into elastic energy
starting point
Em₀ = K = ½ m v²
final point
Em_{f} = + U = ½ k y² + m g y
Emo = Em_{f}
½ m v² = ½ k y² + mgy
k y² + 2 m g y - m v² = 0
we substitute the values and solve the quadratic equation
78.4 y² + 2 80 9.8 y - 80 19.8² = 0
78.4 y² + 1568 y - 31363.2 = 0
y² + 20 y - 400 = 0
y = [- 20 ±√ (20 2 +4 400)] / 2
y = [-20 ± 44.72] / 2
the solutions are
y₁ = 12.36 m
y₂ = 32.36 m
These solutions correspond to the maximum stretch and its rebound.
Therefore maximum stretch is y2 = 32.36 m
Answer: option C.
Fabrics such as cotton and silk are synthetic polymers
Explanation:
Fabrics such as cotton and silk are synthetic polymers because cotton and silk are natural polymers meaning they are gotten from natural source. Cotton is gotten from cotton plants and it is composed of cellulose which is a carbohydrates.
Silk also is gotten from animals I.efrom insect fibre or the cocoons of the larvae of the mulberry silkworm which is a polymer.
Answer:
The total energy of the object does not change is the true statement.
Explanation:
1. The force applied to the object is perpendicular to the movement so doesn't work on it, assuming the table is at the same height in all of its points the only energy we have to analyze is the kinetic energy , because the table top is frictionless by Newton's first law the velocity (v) doesn't change so the kinetic energy is constant and the total energy too.
2. There's no friction in this situation
3. As stated on 1. because the applied force is perpendicular to the movement of the object, there force doesn't work on it.
4. There are over one force on the object, the weight and the normal force table top exerts to the object.
So the only true statement is 1.