Answer:
The rate of change of the height is - 4 ft/s
Solution:
As per the question:
Height of the person, y = 5 ft
The rate at which the person walks away, 
Distance of the spotlight from the wall, x = 40 ft
Now,
To calculate the rate of change in the height,
of the person when, x = 10 m:
From fig 1.
![\Delta ABC[\tex] ≈ [tex]\Delta PQC[\tex]Thus[tex]\frac{BC}{AB} = \frac{PQ}{QC}](https://tex.z-dn.net/?f=%5CDelta%20ABC%5B%5Ctex%5D%20%E2%89%88%20%5Btex%5D%5CDelta%20PQC%5B%5Ctex%5D%3C%2Fp%3E%3Cp%3EThus%3C%2Fp%3E%3Cp%3E%5Btex%5D%5Cfrac%7BBC%7D%7BAB%7D%20%3D%20%5Cfrac%7BPQ%7D%7BQC%7D)

xy = 200 (1)
Differentiating the above eqn w.r.t time t:

Thus
(2)
From eqn (1):
When x = 10 ft
10y = 200
y = 20 ft
Using eqn (2):

The given situation below describes a standing wave because the string is fixed at both ends. A standing wave having three anti-nodes will have a wavelength that is two-thirds the length of the string. After getting the wavelength, this can be multiplied with the frequency to get the wave speed.
For this problem:
wave length = (2/3)(length of string: 68 cm)
wave length = (10/3 cm)
wave speed = wave length x frequency
wave speed = (10/3 cm) x (180 Hz)
wave speed = 600 cm/s or 0.6 m/s
Answer:
rate of fission =5.89*10^3 1\Year
Explanation:
we know that
rate of fission is given as

mass = 1.0 g
avogardo number = 6.02*10^23
molar mass of isotopes 235U =235
Putting all value to get rate of emission
rate of fission 
rate of fission =5.89*10^3 1\Year
Here in this question as we can see there is no air friction so we can use the principle of energy conservation


now here we know that



now plug in all values in above equation

divide whole equation by mass "m"



so height of the ball from ground will be 1.35 m
Answer:
Here Strain due to testing is greater than the strain due to yielding that is why computation of load is not possible.
Explanation:
Given that
Yield strength ,Sy= 240 MPa
Tensile strength = 310 MPa
Elastic modulus ,E= 110 GPa
L=380 mm
ΔL = 1.9 mm
Lets find strain:
Case 1 :
Strain due to elongation (testing)
ε = ΔL/L
ε = 1.9/380
ε = 0.005
Case 2 :
Strain due to yielding


ε '=0.0021
Here Strain due to testing is greater than the strain due to yielding that is why computation of load is not possible.
For computation of load strain due to testing should be less than the strain due to yielding.