Answer:

Explanation:
We have given initial length of the steel guitar l = 1 m
Cross sectional area 
Young's modulus 
Force F = 1500 N
So stress 
We know that young's modulus 
So 

Now strain 


Answer:
180 W
Explanation:
The work done by the man against gravity is equal to its gain in gravitational potential energy:

where
(mg) = 720 N is the weight of the man
is the change in height
Substituting,

The power he must deliver is given by

where
W = 3600 J
t = 20 s is the time taken
Substituting,

Answer: 100 m/s^2
F=ma
Explanation:
50N = 50 kg*m/s^2
500g = 0.5 kg
F=ma
a = F/m
a = (50 kg*m/s^2)/(0.5 kg)
a = 100 m/s^2
Answer is: 1973.17N aprox.
step by step in the pic below
Answer:
Approximately
.
Explanation:
Since the result needs to be accurate to three significant figures, keep at least four significant figures in the calculations.
Look up the Rydberg constant for hydrogen:
.
Look up the speed of light in vacuum:
.
Look up Planck's constant:
.
Apply the Rydberg formula to find the wavelength
(in vacuum) of the photon in question:
.
The frequency of that photon would be:
.
Combine this expression with the Rydberg formula to find the frequency of this photon:
.
Apply the Einstein-Planck equation to find the energy of this photon:
.
(Rounded to three significant figures.)