You first find the mass and the volume of that object. Then you divide mass ÷ volume
Answer:
Lens at a distance = 7.5 cm
Lens at a distance = 6.86 cm (Approx)
Explanation:
Given:
Object distance u = 12 cm
a) Focal length = 20 cm
b) Focal length = 16 cm
Computation:
a. 1/v = 1/u + 1/f
1/v = 1/20 + 1/12
v = 7.5 cm
Lens at a distance = 7.5 cm
b. 1/v = 1/u + 1/f
1/v = 1/16 + 1/12
v = 6.86 cm (Approx)
Lens at a distance = 6.86 cm (Approx)
As long as the sound is inside the helmet of your space suit, it will travel
at the same speed as it would on Earth, through the same mixture of gases
at the same pressure. Once it passes through the visor of your space helmet,
its 'speed' has no meaning, since there's nothing for sound to travel through on
the moon, and it doesn't travel at all.