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3 years ago

13

When light generated by a lamp in a light microscope passes into a lens, the speed of the light _______ because the glass lens h

as a _______ refractive index than the air from which the light came.

1 answer:

Alina [70]3 years ago

6 0

Answer:

the answer is slows and greater

Hopes it helps!

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A skater goes into a spin with her arms pulled in (close to her body). When she stretches her arms out: A) her angular speed ω d

musickatia [10]

Answer:

When she stretches her arms out,<em> B) her angular speed ω increases due to her moment of inertia decreasing</em>

Explanation:

The angular momentum of a rotating object is defined as the product of its moment of inertia and angular speed.

<em>L = I ω</em>

<em>where</em>

<em>L is the angular momentum</em>
<em>I is the moment of inertia</em>
<em>ω is the angular speed</em>

<em />

According to the principle of conservation of angular momentum, if there is no external torque, angular momentum of the skater must remain conserved. If the initial and final moment of inertia is <em>I_i and I_f </em>while corresponding angular velocities are <em>ω_i and ω_f , </em>then the principle of conservation of angular momentum can be expressed as the following equation:

<em>(I_f) (ω_f) = (I_i) (ω_i)</em>

<em>ω_f / ω_i = I_i / I_f</em>

<em />

From the expression above, we can see that if the moment of inertia decreases, angular velocity would increase to conserve angular momentum of the skater.

Therefore, When she stretches her arms out,<em> her angular speed ω increases due to her moment of inertia decreasing.</em>

5 0

4 years ago

2001240Determine the specific kinetic energy of a mass whose velocity is 40 m/s, in kJ/kg.

guapka [62]

Answer:

The specific kinetic energy of a mass is 0.8 kJ/kg

Explanation:

Given that,

Velocity = 40 m/s

Specific kinetic energy is the kinetic energy per unit mass.

We need to calculate the specific kinetic energy

Using formula of specific kinetic energy

$K.E=\dfrac{\dfrac{1}{2}mv^2}{m}$

$K.E=\dfrac{v^2}{2}$

Put the value into the formula

$K.E=\dfrac{40^2}{2}$

$K.E=800\ J/kg$

We know that,

1 kJ = 1000 J

or, 1J=0.001 KJ

The specific energy is

$K.E=800\times0.001$

$K.E=0.8\ kJ/kg$

Hence, The specific kinetic energy of a mass is 0.8 kJ/kg

6 0

3 years ago

Which of the following statements is true concerning mechanical waves and electromagnetic waves?

Over [174]

Answer:

B

Explanation:

Electromagnetic spectrum includes visible light which we see all the time reflecting off objects to give them colours, mechanical waves like sound require something to move in, its the reason why people say you can't scream in space because space is a giant vacuum. No not the kind you use to clean up the mess you made from breakfast. The kind that has no air. So sound can be heard on earth as it is not a vacuum, air moves freely and transfers sounds vibrations all around you to be absorbed by walls and other stuff in comes in contact with.

Extra information:

Sound travels further in water because the molecules are closer together meaning that transferring the energy is easier. This is how Blue wales can communicate from hundreds of miles away.

3 0

3 years ago

An engine performs 2700 J of work on a scooter. The scooter and rider have a combined mass of 150 kg. If the scooter started at

Finger [1]

Due to the principle of conservation of energy, the work done by the engine to move the scooter converts into kinetic energy of the scooter:
$W=K= \frac{1}{2} M v^2$
where M is the combined mass of scooter and rider, and v is the velocity of the scooter. Therefore, we can find the velocity as:
$v= \sqrt{ \frac{2W}{M} } = \sqrt{ \frac{2\cdot 2700 J}{150 Kg} }=6 m/s$

6 0

4 years ago

In a pulley system, two blocks are connected by a rope as shown below. The coefficient of static friction between block A and th

umka21 [38]

Hi there!

We can begin by doing a summation of forces for each block.

Block A:

This block has the force of tension (in direction of acceleration +) and static friction (opposite direction -) acting on it. Thus:

$\Sigma F_A = T - F_s\\\\m_Aa = T - \mu m_Ag$

Block B:

This block has the force of tension (opposite of acc. -) and gravity (in direction of acc +), working on it.

$\Sigma F_B = m_Bg - T\\\\ m_Ba = m_Bg - T$

Add both of the expressions and solve for the maximum mass of Block B.

$\Sigma F = m_Bg - T + T - \mu m_Ag\\\\a(m_A + m_B) = m_Bg - \mu m_Ag$

To find the minimum value, we can set a = 0, so:

$0 = m_Bg - \mu m_Ag\\\\\mu m_Ag = m_B g\\\\0.8(20)(9.8) = m_B (9.8)\\\\m_B = \frac{0.8(20)(9.8)}{9.8)} = \boxed{16 kg}$

The block must weigh <u>> 16 kg</u> for block A to move.

5 0

3 years ago