Answer:
4.9 x 10⁻⁴N
Explanation:
Given parameters: 
Mass of the vertical strand of spiderweb  = 5 x 10⁻⁵kg 
Unknown: 
Tension in the vertical strand  = ? 
Solution: 
The tension is the vertical strand will be the weight of the strand. 
   Weight of strand  = mg 
 m is the mass 
 g is the acceleration due to gravity = 9.8m/s² 
 Tension in the vertical strand  = 5 x 10⁻⁵kg  x 9.8m/s² 
Tension in the vertical strand  = 4.9 x 10⁻⁴N
 
        
             
        
        
        
Answer:
E. greater than the angle of incidence.
Explanation:
Snell's law states that:
 (1)
 (1)
where
 are the refractive index of the first and second medium
 are the refractive index of the first and second medium
 are the angle of incidence and refraction, respectively
 are the angle of incidence and refraction, respectively
For light moving from water to air, we have:
 (index of refraction of water)
 (index of refraction of water)
 (index of refraction of air)
 (index of refraction of air)
Substituting into (1) and re-arranging the equation, we get

which means that

so, the correct answer is
E. greater than the angle of incidence.
 
        
                    
             
        
        
        
Mirrors don't cause refraction.
A convex mirror could cause parallel rays to REFLECT away from each other.
        
             
        
        
        
Answer:
Check the first and the third choices:
<u><em /></u>
- <u><em>a. The temperature of a gas is directly proportional to its volume</em></u>
- <u><em>b. The temperature-to-volume ratio of a gas is constant.</em></u>
Explanation:
Rewrite the table for better understanding:
Temperature of gas (K)     Volume of gas (L)
      298                                     4.55
      315                                      4.81
      325                                     4.96
      335                                        ?
Calculate the ratios temperature to volume with 3 significant figures:
Then, those numbers show a <u><em>constant temperature-to-volume ratio</em></u>, which may be expressed in a formula as:
- Temperature / Volume = constant, which is a directly proportional variation (the volume increases in a constant proportion to the increase of the temperature).
Hence, the correct choices are:
- The temperature of a gas is directly proportional to its volume (first statement), and
- The emperature-to-volume ratio of a gas is constant (third statement).