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3 years ago

Why is it not necessary for radio telescope surfaces to be as smooth as a mirror?

1 answer:

8 0

It doesn't on account of radio waves are longer than optical waves. Radio waves are a sort of electromagnetic radiation with wavelengths in the electromagnetic range longer than infrared light. These long waves are in the radio locale of the electromagnetic range.

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A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of the wood?

Bingel [31]

Density review

A B

What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3? d = .85 g/cm3

A piece of wood that measures 3.0 cm by 6.0 cm by 4.0 cm has a mass of 80.0 grams. What is the density of the wood? Would the piece of wood float in water? (volume = L x W x H) d = 1.11 gm/cm3

8 0

3 years ago

A pulley lifts a 72-N load with a force of 24-N. The input distance is 2m and the output distance is 0.5m. What is the efficienc

Debora [2.8K]

Answer:

Explanation:

Work done on the lever ( input energy ) = force applied x input distance

= 24 N x 2m = 48 J

Work done by the lever ( output energy ) = load x output distance

= 72 N x 0.5m = 36 J

efficiency = output energy / input energy

= 36 J / 48 J

= 3 / 4 = .75

In percentage terms efficiency = 75 % .

5 0

3 years ago

Astaten whats 2+2 answer

alexandr402 [8]

Answer:

2+2=4

Explanation:

6 0

3 years ago

if a 5-kg bowling ball is projected upward witha velocity of 2.0 m/s, then what is the recoil velocity of the Earth(mass=6.0×10^

vitfil [10]

by the concept of momentum conservation we can say

if net force on a system of mass is ZERO then its momentum will remain conserved

Here a ball is projected upwards so if we take Ball + Earth as a system then total momentum of the system will remain conserved

Initially when ball is on the surface of earth the system has zero momentum and hence we can say after throwing the ball momentum of earth + ball must be zero

now using same equation we can say

$P_{ball} + P_{earth} = 0$

$m_1v_1 + m_2v_2= 0$

given that

$m_1 = 5 kg$

$v_1 = 2 m/s$

$m_2 = 6 * 10^{24} kg$

from above equation velocity of earth will be

$v_2 = \frac{m_1 v_1}{m_2}$

$v_2 = \frac{5*2}{6 * 10^{24}}$

$v_2 = 1.67 * 10^{-24} m/s$

so above will be the recoil speed of earth

3 0

3 years ago

Assume: The bullet penetrates into the block and stops due to its friction with the block. The compound system of the block plus

charle [14.2K]

Answer:

The total energy of the composite system is 7.8 J.

Explanation:

Given that,

Height = 0.15 m

Radius of circular arc = 0.27 m

Suppose, the entire track is friction less. a bullet with a m₁ = 30 g mass is fired horizontally into a block of wood with m₂ = 5.29 kg mass. the acceleration of gravity is 9.8 m/s.

Calculate the total energy of the composite system at any time after the collision.

We need to calculate the total energy of the composite system

Total energy of the system at any time = Potential energy of the system at the stopping point

$E=mgh+Mgh$