Answer:
The answer is "telescopes".
Explanation:
Throughout ancient times, astronomical observatories have indeed been available, and so many historical locations were reserved for astronomical observations. All contemporary astronomers lacked within those older telescopes were lenses until 1610. A telescope is indeed an instrument used to view far-off objects. Telescopes often are being used to look at planets and stars.
Answer:
The weight of measuring stick is 9.8 N
Explanation:
given information:
the mass of the rock, 
= 1 kg
measuring stick, x =1 m
d = 0.25 m
to find the weight of measuring stick, we can use the following equation:
τ = Fd
τ = 0
- 
= 0
F_{r} = the force of the rock
F_{s} = the force of measuring stick
= m g
= 1 kg x 9.8 m/s
= 9.8 N
thus, the weight of measuring stick is 9.8 N
I’m pretty sure it’s circuit three.
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.
