Answer:
The height (in m) above the floor of the top and bottom of the smallest mirror in which he can see both the top of his head and his feet is;
1.835 m and 0.88 m.
Explanation:
Here we have the total height of the man as
1.76 + 0.15 = 1.91 m
The mirror is positioned such that the person can see both the top of his head and his feet
We have the eyes are 0.15 m below the top of the head, therefore by the law of reflection, the incident and reflected angle must be equal.
Hence, the light from the top of his head and then reflected to his eyes forms a isosceles triangle, with the base being the distance of the eye to the top of his head and the top of the triangle is on the mirror.
The height of the mirror is then
1.91 - 0.15/2 = 1.835 m
Similarly, the distance from the eye to the feet is 1.76, therefore, the base of the mirror is positioned at 1.76/2 or 0.88 m above the ground.
Answer:
Explanation:
The mechanical work done by the load placed on a fiber if the fiber deforms by 3 nano-meter can be given in relation to the energy stored in a stretched fiber.
- We know according to the Hooke's law within the elastic limit the stress is directly proportional to the strain. The constant introduced is called stiffness constant defined as the magnitude of load applied for the deformation of one unit in the dimension of the object.
<u>The energy stored in a stretched fiber is equal to the work done:</u>
where:
k = stiffness constant
deformation in the fiber = 
<span>A battery creates a potential difference, or voltage, which is really just storing electrical potential energy just as a pump would by moving water up against gravity, thereby storing gravitational potential energy. To complete the analogy, as current flows through the circuit, this potential energy is released and can be used by the components in the circuit. This is the same as water falling back down and turning some wheel or turbine and converting its gravitational potential energy into mechanical energy.</span>
Answer:
We must be approximately at least 1.337 meters away to be exposed to an intensity considered to be safe.
Explanation:
Let suppose that intensity is distributed uniformly in a spherical configuration. By dimensional analysis, we get that intensity is defined by:
(1)
Where:
- Intensity, measured in watts per square meter.
- Radius, measured in meters.
If we know that 
and 
, then the radius is:
![r = \sqrt[3]{\frac{3\cdot \dot W}{4\pi\cdot I} }](https://tex.z-dn.net/?f=r%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B3%5Ccdot%20%5Cdot%20W%7D%7B4%5Cpi%5Ccdot%20I%7D%20%7D)
![r = \sqrt[3]{\frac{3\cdot (10\,W)}{4\pi\cdot \left(1\,\frac{W}{m^{2}} \right)} }](https://tex.z-dn.net/?f=r%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B3%5Ccdot%20%2810%5C%2CW%29%7D%7B4%5Cpi%5Ccdot%20%5Cleft%281%5C%2C%5Cfrac%7BW%7D%7Bm%5E%7B2%7D%7D%20%5Cright%29%7D%20%7D)
We must be approximately at least 1.337 meters away to be exposed to an intensity considered to be safe.
