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3 years ago

Which scientist was the first to use the telescope in astronomy

Physics

1 answer:

Mashutka [201]3 years ago

4 0

Answer:

Galileo Galilei

Explanation:

although Galileo was not the scientist who invented the telescope, he was the first to use it to observe celestial objects. he used the telescope in 1609. his discovery included more accurate information about the moon, the sun and some of the planets.

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A solenoidal coil with 21 turns of wire is wound tightly around another coil with 350 turns. The inner solenoid is 25.0 cm long

77julia77 [94]

A) We need to calculate the Magnetic flux of a Solenoid,

$\Phi = BA$

Where B is the magnetic field and A the Area.

$B=\frac{\mu_0 N_2 I}{l}$

Here \mu_0 is the permeability constant, I the current and N number of turns.

Replacing we have,

$\Phi = \frac{\mu_0 N_2 I}{l}(\pi r^2)$

$\Phi = \frac{(4\pi*10^{-7})(350)(0.12)}{25*10^{-2}} (\pi*\frac{2.5*10^{-2}}{2}^2)$

$\Phi = 1.036*10^{-7}Wb$

B) We calculate the mutual inductance, so

$M=\frac{N_1 \Phi}{i}$

$M=\frac{21*1.036*10^{-7}}{0.12}$

$M=1.813*10^{-5}H$

c) We calculate the emf

$\epsilon = -M \frac{dI}{dt}$

$\epsilon = -1.813*10^{-5}*1700$

$\epsilon= -0.030V$

3 0

3 years ago

A skater of mass 60 kg has an initial velocity of 12 m/s. He slides on ice where the frictional force is 36 N. How far will the

Alexus [3.1K]

Answer:

d = 120 [m]

Explanation:

In order to solve this problem, we must use the theorem of work and energy conservation. Where the energy in the final state (when the skater stops) is equal to the sum of the mechanical energy in the initial state plus the work done on the skater in the initial state.

The mechanical energy is equal to the sum of the potential energy plus the kinetic energy. As the track is horizontal there is no unevenness, in this way, there is no potential energy.

E₁ + W₁₋₂ = E₂

where:

E₁ = mechanical energy in the initial state [J] (units of Joules)

W₁₋₂ = work done between the states 1 and 2 [J]

E₂ = mechanical energy in the final state = 0

E₁ = Ek = kinetic energy [J]

E₁ = 0.5*m*v²

where:

m = mass = 60 [kg]

v = initial velocity = 12 [m/s]

Now, the work done is given by the product of the friction force by the distance. In this case, the work is negative because the friction force is acting in opposite direction to the movement of the skater.

W₁₋₂ = -f*d

where:

f = friction force = 36 [N]

d = distance [m]

Now we have:

0.5*m*v² - (f*d) = 0

0.5*60*(12)² - (36*d) = 0

4320 = 36*d

d = 120 [m]

7 0

3 years ago

A 140-kg merry-go-round in the shape of a uniform, solid, horizontal disk of radius 1.50 m is set in motion by wrapping a rope a

RUDIKE [14]

Answer:

The constant force is 263.55 newtons

Explanation:

There's a rotational version of the Newton's second law that relates the net torque on an object with its angular acceleration by the equation:

$\tau = I\alpha$ (1)

with τ the net torque and α the angular acceleration. It’s interesting to note the similarity of that equation with the well-known equation F=ma. I that is the moment of inertia is like m in the linear case. The magnitude of a torque is defined as

$\tau = Fr\sin \theta$

with F the force applied in some point, r the distance of the point respect the axis rotation and θ the angle between the force and the radial vector that points toward the point the force is applied, in our case θ=90 and sinθ=1, then (1):

$Fr = I\alpha$ (2)

Because the applied force is constant the angular acceleration is constant too, and for constant angular acceleration we have that it's equal to the change of angular velocity over a period of time:

$\alpha=\frac{0.800}{2.00}=0.40 \frac{rev}{s^{2}}$