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Pavlova-9 [17]
3 years ago
12

Astronomical observatories have been available since ancient times, and many cultures set aside special sites for astronomical o

bservations. The thing modern observatories have that was missing from these older observatories until about 1610 was __________________. Group of answer choices
Physics
1 answer:
Vlada [557]3 years ago
8 0

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.

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lyudmila [28]

Answer:

Explanation:

Bobbitt worm ( Eunice aphroditois). This segmented polychaete marine worm can attain lengths of 10 feet. It bristles...

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5 0
3 years ago
A truck on the freeway originally moving at 6.6 meters/second accelerates uniformly with acceleration a = 2.8 meters/second2 for
Sonja [21]

Answer:

139.514 metres

Explanation:

Initial velocity of the truck = 6.6 m/s

Acceleration of the truck = 2.8 m/s^2

Time interval = 7.9 s

Therefore we use the formula,

s = ut + 1/2 at^2

*where s(the distance travelled)...u(the initial velocity)...t(the time period)

; s = 6.6(7.9) + 1/2 (2.8)(7.9)^2

; s = 52.14 + 87.374

The distance moved by the truck = 139.514m

8 0
2 years ago
The 1350-kg car has a velocity of 24 km/h up the 8-percent grade when the driver applies more power for 18 s to bring the car up
Brrunno [24]

Answer:

Explanation:

We shall apply concept of impulse to solve the problem  .

Impulse = force x time

impulse = change in momentum

force x time = change in momentum

initial speed u = 24 km/h = 6.67 m /s

final speed v = 65 km/h = 18.05 m /s

change in momentum = m v - mu

= m ( v-u )

= 1350 ( 18.05 - 6.67 )

= 15363 kg m/s

F x 18 = 15363

F = 853.5 N .

4 0
3 years ago
A truck is traveling at 27 m/s down the interstate highway where you are changing a flat tire. frequency of 185 Hz.
Reil [10]

Answer:

(a) the observed frequency is 200 Hz

(b) the observed frequency is 188 Hz.

Explanation:

speed of the truck, Vs = 27 m/s

frequency of the truck as it approaches, Fs = 185 Hz

(a) Apply Doppler effect to determine the frequency you will hear.

As the truck approaches you, the observed frequency will be higher than the source frequency because of decrease in distance.

F_s = F_o [\frac{V}{V_S + V} ]

Where;

Fo is the observed frequency which is the frequency you will hear.

V is speed of sound in air

F_s = F_o [\frac{V}{V_S + V} ]\\\\185 = F_o [\frac{340}{27 + 340} ]\\\\185 = F_o (0.926)\\\\F_o = \frac{185}{0.926}\\\\F_o = 199.78 \ Hz

F_o = 200 \ Hz

(b) Apply the following formula for a moving observer and a moving source;

F_o = F_s[\frac{V-V_o}{V} ](\frac{V}{V-V_S} )

The observed frequency is negative since you are driving away from the truck and the source frequency is also negative since it is driving towards you.

F_o = F_s[\frac{V-V_o}{V} ](\frac{V}{V-V_S} )\\\\F_o = 185[\frac{340-22}{340} ](\frac{340}{340-27} )\\\\F_o = 185(0.9353)(1.0863)\\\\F_o = 188 \ Hz

5 0
3 years ago
A 11kg block slides up a 30° inclined plane at a constant velocity. The coefficient of friction between the block and the plane
astra-53 [7]

Answer:

The magnitude of the applied force is 94.74 N

Explanation:

Mass of the block, m = 11 kg

Angle of inclination of the plane, \theta = 30^{\circ}

Friction coefficient, \mu_{k} = 0.2

Now,

Normal force that acts on the block is given by:

F_{N} = mgcos\theta + Fsin\theta           (1)

Now, to maintain the equilibrium parallel to ramp the forces must be balanced.

Thus

Fcos\theta = \mu_{k}F_{N}                       (2)

From eqn (1) and (2)

Fcos\theta = \mu_{k}(mgcos\theta + Fsin\theta)

F(cos\theta - \mu_{k}sin\theta) = \mu_{k}mgcos\theta

F = \frac{\mu_{k}mgcos\theta}{cos\theta - \mu_{k}sin\theta}

F = \frac{0.2\times 11\times 9.8cos30^{\circ}}{cos30^{\circ} - 0.2\times sin30^{\circ}}

F = 94.74 N

3 0
3 years ago
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