Answer:
54 N
Explanation:
Draw a free body diagram. There are four forces acting on the balloon. Buoyant force pushing the balloon up, gravity pulling the helium down, gravity pulling the balloon skin down, and gravity pulling the load down.
Apply Newton's second law:
∑F = ma
B − Wh − Wb − L = ma
When the load is at a maximum, the acceleration is 0:
B − Wh − Wb − L = 0
B − Wh − Wb = L
B − mh g − Wb = L
The mass of the helium is its density times its volume:
B − ρh Vh g − Wb = L
Buoyant force is defined as B = ρVg, where ρ is the density of the displaced fluid (in this case, air), V is the volume of the displaced fluid, and g is acceleration of gravity. Since the volume of displaced air = the volume of the helium:
ρa V g − ρh V g − Wb = L
(ρa − ρh) V g − Wb = L
Given that ρa = 0.90 kg/m³, ρh = 0.178 kg/m³, V = 20 m³, g = 9.8 m/s², and Wb = 88 N:
(0.9 − 0.178) (20) (9.8) − (88) = L
L = 53.5 N
Rounded to 2 sig-figs, the maximum load that can be supported is 54 N.
Answer:
Refracted rays travel through a boundary into a new medium.
Explanation:
Refracted rays travel through a boundary into a new medium. is only true for refraction.
The angle of incidence is the same for angle of refraction, is not true for refraction. Refraction follows Snell's law, states that ratio of the sine of the angle of refraction and the sine of the angle of incidence is always constant and equivalent to the ratio of phase velocities of the two mediums it is passing through.
Refracted rays change direction and go back to the original medium is false for refraction however, it is true for reflection.
If it's not falling through air, water, smoke, or anything else,
and gravity is the only force on it, then its speed increases
at a constant rate ... 9.8 meters per second for every second
it falls. (That's the number on Earth. It's different in other places.)
