Explanation:
Lasers produce a narrow beam of light in which all of the light waves have very similar wavelengths. The laser's light waves travel together with their peaks all lined up, or in phase. This is why laser beams are very narrow, very bright, and can be focused into a very tiny spot.
I believe the correct answer is B
Fire extinguishers are typically red. Goes along with the red fire trucks and red being a color of emergency. While there isn't any standard, if we decided to change the colors of the fire extinguisher, people would be very confused and given the context, it could cost people's lives, so I'm thinking red will be the color of fire extinguishers for a while to come.
<span />
Answer:
0.001152m
Explanation:
Linear expansivity of a material is the change in length of the material per unit length per degree rise in temperature. Mathematically,
¢ = ∆L/L1∆°C
¢ is the linear expansivity of the material = 12 x 10⁻⁶ °C⁻¹
Where ∆L is the change in length = L2-L1
L2 is the final length = ?
L1 is the initial length = 12m
∆°C is the change in temperature = °C2 - °C1 = 50-(-30) = 80°C
Substituting this values inside the formula to get the final length L2 after expansion, we have;
12 x 10⁻⁶ °C⁻¹ = L2-12/12×80
12 x 10⁻⁶ °C⁻¹ = L2-12/960
L2-12= 960×12 x 10⁻⁶ °C⁻¹
L2-12 = 0.001152
L2 = 12+0.001152
L2 = 12.001152m
Expansion will be the change in length L2-L1 = 12.001152-12
= 0.001152m
The expansion cracks between the slabs should be 0.001152m wide to prevent buckling
