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Inga [223]
3 years ago
11

What structure is used to focus light in a reflecting telescope?

Physics
1 answer:
zmey [24]3 years ago
4 0

Answer:

Concave mirror

Explanation:

  • Reflecting telescopes is a type of telescope that uses mirrors instead of lens. This is because mirrors are lighter and thus are easier to make perfectly smooth as compared to lenses.
  • Reflecting telescopes use concave mirrors for the purposes of bringing light gathered to a certain focus.
  • <em><u>Concave mirror in reflecting telescopes collects parallel rays from the object and forms an image at the focal point. </u></em>

<em><u /></em>

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Periodic motion can BEST be defined as motion
koban [17]

Answer:

C

Explanation:

repeated in intervals of time

8 0
3 years ago
A cord of negligible mass runs around two massless, frictionless pulleys. A canister with mass m = 20 kg hangs from one pulley.
photoshop1234 [79]

(a) 196 N

The equation of the forces on the side of the cord where the force F is applied is:

F-T=0 (1)

where T is the tension in the cord.

On the other side of the cord, the equation of the forces on the canister is

T-mg = ma (2)

where

m = 20 kg is the mass of the canister

g=9.8 m/s^2 is the acceleration of gravity

a is the acceleration

From (1),

T=F

Substituting into (2),

F-mg = ma\\F=m(g+a)

We want the canister to move at constant speed, so

a = 0

And therefore:

F=mg=(20)(9.8)=196 N

b) 2.0 cm

The cord is inextensible, this means that the acceleration of its parts are the same. Therefore, the acceleration of the free end must be the same as the acceleration of the canister: and this means that the two parts also cover the same distance in the same time.

Therefore, the free end of the cord must be moved exactly the same as the canister, by 2.0 cm.

c) 3.92 J, the same

The work done by the tension in the cord is

W_T = T d

where

T is the tension

d = 2.0 cm = 0.02 m is the displacement

As we said in part (a), the tension in the cord is equal to the force applied to the free end:

T = F

So

T = 196 N

Therefore, the work done by the tension is

W=(196)(0.02)=3.92 J

And since the force applied (F) is the same, then the work done by you when pulling the cord is exactly the same.

(d) -3.92 J

The weight of the canister is

F_g = mg =(20 kg)(9.8 m/s^2)=196 N

However, the direction of the force of gravity is opposite to the displacement. Therefore, the work done by gravity is negative:

W_g = - F_g d

And substituting,

W_g=-(196)(0.02)=-3.92 J

(e) Zero

The net work done on the canister can be simply calculated by adding the work done by the tension in the cord and the weight of the canister:

W=W_T+W_g = 3.92 + (-3.92 ) = 0

This is in agreement with the work-energy theorem, which states that the work done on an object is equal to its change in kinetic energy. In this situation, the canister is moving at constant speed, so its kinetic energy is not change: therefore,

\Delta K = 0 (change in kinetic energy = 0)

and so, the work done on it is also zero.

(f) The pulley system changes the direction of the force applied

This is a simple pulley system, which means  that the system does not multiply the force applied in input. In fact, the mechanical advantage of the system is

MA=\frac{F_{out}}{F_{in}}

where:

F_{out} is the output force, which is the weight of the canister

F_{in} is the force in input, which is F

So, the mechanical advantage is 1:

MA=\frac{196 N}{196 N}=1

From a point of view of energy, therefore, there is no advantage in this system.

However, the advantage offered by the pulley system concerns the direction of the force: in fact, it changes the direction of the applied force (which is F, downward) into the tension of the cord (which is upward on the canister).

6 0
3 years ago
A student pushes a 5 kg box initially at rest along a flat, rough table with a rightward force of 10 N. The frictional force act
Pie

Answer:

Please find attached pdf

Explanation:

Download pdf
8 0
3 years ago
A woman is riding a jet ski at a speed of 26 m/s and notices a seawall straight ahead. the farthest she can lean the craft in or
castortr0y [4]

she can stop about 16 feet before hitting it

7 0
3 years ago
A coin of mass m rests on a turntable a distance r from the axis of rotation. The turntable rotates with a frequency of f. What
Crank

Answer:

\mu = \frac{r (2\pi f)^{2}}{g}

Explanation:

N = normal force acting on the coin

Normal force in the upward direction balances the weight of the coin, hence

N = mg

f = frequency of rotation

Angular velocity of turntable is hence given as

w = 2\pi f

r = distance from the axis of rotation

\mu = minimum coefficient of static friction

static frictional force is given as

f = \mu N\\f = \mu mg

The  static frictional force provides the necessary centripetal force , hence

Centripetal force = Static frictional force

m r w^{2} = \mu mg\\r w^{2} = \mu g\\\\\mu = \frac{r w^{2}}{g} \\\mu = \frac{r (2\pi f)^{2}}{g}

3 0
3 years ago
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