Answer:A7.50kg object is hung from the bottom end of a vertical spring fastened to an overhead beam. The object is set into vertical oscillations having a period of2.30s. Find the force constant of the spring.
N/m
Explanation:
Answer:
6.875 m/s
Explanation:
The force is variable which is given by
F(x) = 18 - 0.53 x
mass of the box, m = 8.9 kg
initially it is at rest at x = 0
Let the velocity is v after travelling a distance of 15 m.
According to the work energy theorem, the work done by all the forces is equal to the change in kinetic energy of the body.
Work done = change in kinetic energy



18 x 15 - 0.265 x 15 x 15 = 4.45 x v²
270 - 59.625 = 4.45 v²
v² = 47.275
v = 6.875 m/s
Thus, the final velocity of the box is 6.875 m/s.
Answer:
c. expanded polyurethane
Explanation:
Thermal performance of a building fabric is measured in terms of heat loss and is expressed as U-value or R-value. U-value is the rate of heat transferred through a structure divided by the difference in temperature across the structure with a unit of measurement of W/m²K.You can calculate the U-value of a by getting the reciprocal of the sum of thermal resistances , R, making the building material.
If you have the value of R, then U=1/R
Material size R U
plywood 1" 1.25 0.8
Poured concrete 2" 0.99 1.010
Expanded polyurethane 1" 6.5 0.1538
Asbestos shingles 1" 0.03 33.33
The material with lowest U-value is expanded polyurethane
Answer:
greater than 0.10
Explanation:
The null hypothesis is:

The alternate hypotesis is:

Our test statistic is:

In which X is the statistic,
is the mean,
is the standard deviation and n is the size of the sample.
We have that:

We are testing if X is greater than 0.45, so our pvalue is 1 subtracted by the pvalue of z = t = 0.45.
z = 0.45 has a pvalue of 0.6736
1 - 0.6735 = 0.3264
So our pvalue is 0.3264, which is greater than 0.10.
So the correct answer is:
greater than 0.10