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wolverine [178]
3 years ago
6

1. Astronomical observatories have been available since ancient times, and many cultures set aside special sites for astronomica

l observations. The thing modern observatories have that was missing from these older observatories until about 1610 was: a. a dark site, where lights did not get in the way b. graduate students or other assistants for sharing the astronomer’s work c. a method of keeping good records d. a way of measuring from what general direction in the sky a beam of light was coming e. telescopes
Physics
1 answer:
nydimaria [60]3 years ago
4 0

Answer:

e telescopes

Explanation:

may i be marked brainliest?

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An object that has a small mass and an object that has a large mass have the same momentum. which object has the largest kinetic
castortr0y [4]
The larger mass object would have more kinetic energy. 1) its heavier 2) it covers a larger area 3) the more mass an object has, the larger the kinetic energy because of its weight.
6 0
3 years ago
Radio waves travel 300,000,000 m/s. The frequency is 101,700,000. ehats the wavelength​
Nesterboy [21]

Answer:

we have formula of frequency :

frequency(f)= speed of sound(c)/wavelength(λ)

for wavelength we swipe it with frequency as follows

λ=c/f

λ=300,000,000/101,700,000

λ=2.949

8 0
3 years ago
A circular disc of mass 20kg and radius 15cm is mounted in an horizontal cylindrical axle of radius
disa [49]

Using the concepts of energy, rotational Newton's second law and rotational kinematics we can find the kinematic energy of the system formed by the disk and the cylindrical axis

          KE = 0.23 J

given parameters

  • Disk radius R = 15 cm = 0.15 m
  • Cylinder radius r = 1.5 cm = 0.0015 m
  • Disk mass M = 20 kg
  • Time t = 1.2 s
  • Force F = 12 N

to find

  • Kinetic energy (KE)

This exercise must be solved in parts:

1st part. Endowment kinetic energy is the energy due to the circular motion of an object and is described by the equation

         KE = ½ I w²

Where KE is the kinetic energy, I the moment of inertia and w the angular velocity

The moment of inertia is a magnitude that measures the inertia for rotational movement, it is a scalar quantity, therefore it is additive. In this system it is composed of two bodies, the disk and the cylindrical axis, for which the total moment of inertia it is

         I_{ total} = I_{ disk} + I_{ cylinder}

the moments of inertia with respect to an axis passing through the center of mass are tabulated

disk          I_{disk} = ½ M R²

cylinder   I_{cylinder} = ½ m r²

where M and m are the masses of the disk and cylinder respectively, R and r their radii

         I_{total} = ½ (M R² + m r²) = ½ M R² ( 1 + \frac{m}{M} \ (\frac{r}{R})^2 )

         I_{total} = ½ M R² ( 1+ \frac{m}{20}  (\frac{0.015}{0.15} )^2 ) = \frac{1}{2} M R² (1 + 0.005 m)

As the shaft mass  is much lighter than the disk mass , the last term is very small, which is why we despise it.

         I_{total} = ½ M R²

2nd part. Let's use Newton's second law for endowment motion

        τ = I α

        α = \frac{\tau }{I_{total}}l

        τ = F R

        α = \frac{F \ R}{I_{total}}

With the rotational kinematics expressions, we assume that the system starts from rest (w₀ = 0)

        w = w₀ + α  t

where w is the angular velocity, alpha is the angular acceleration and t is the time

        w = 0 + \frac{\tau }{I_{total}} \ t

we substitute in the kinetic energy equation

        KE = ½ I_{total}  ( \frac{ \tau }{I_{total}} \ t )²

        KE = ½ \frac{ \tau^2 }{I_{total}} \ t^2

let's substitute

        KE = \frac{F^2 \ R^4}{M \ R^2 } \ t^2

        KE = F² R² t² / M

let's calculate

        KE = 12² 0.15² 1.2² / 20

        KE = 0.23 J

With the concepts of energy and rotational kinematics we can find the kinetic energy of the system is

       KE = 0.23 j

learn more about rotational kinetic energy here:

brainly.com/question/20261989

4 0
2 years ago
Suppose students experiment with the tube and a variety of darts. Some darts have higher masses than others but are the same aer
san4es73 [151]

Answer:

The dart with the small mass will travel the farthest distance.

Explanation:

Acceleration is proportional to force times mass, and inertia is proportional to mass. Inertia is the reluctance of a moving body to stop, and a stationary body to start moving (inertia increses with mass). Assuming they both have the same aerodynamic design, and that they are both launched with the same force applied for the same time duration, the dart with less small mass will accelerate faster than the big mass dart. From this we can see that the small dart will have covered a longer distance before the effect of the force stops, when compared to the more massive dart.

5 0
3 years ago
1) What would the average acceleration be for a car at a stoplight that speeds up to 20 m/s in 10 seconds (in m/s^2)
Alexxx [7]
1.)
Velocity is in m/s, and acceleration is in m/s^2 like you said. Because of this, we can calculate this by dividing the speed by the time it took to get to that speed.
(20 meters/second) / 10 seconds = 2 meters/ second^2

2.)
Same thing with the first one.
(100 meters/second) / 4 seconds = 25 meters / seconds^2
7 0
3 years ago
Read 2 more answers
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