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rodikova [14]
2 years ago
9

If a 75-kg skater starts his skate at 8.0m, at his lowest point (height = 0), what is

Physics
1 answer:
Tanya [424]2 years ago
6 0
Mgh= 1/2 m v^2
gh= 1/2 v^2 9.8 * 8=  1/2 v^2
solve for v
V = sqrt(2gH)where H = 8 m.
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Due to radiation and absorption, what is the maximum flame temperature in a fire?
ludmilkaskok [199]

The maximum flame temperature in a fire is 1500-1600K due to radiation and absorption.

<h3>What do you mean by radiation and absorption?</h3>

In physics, matter (usually electrons bound in atoms) absorbs electromagnetic radiation in order to convert the energy of a photon into the internal energy of the absorber (for example, thermal energy). Attenuation, or the steady decrease in light wave intensity as it travels through a medium, is a prominent effect. In some circumstances (optics), the medium's transparency changes by a factor that varies as a function of wave intensity, leading to saturable absorption (or nonlinear absorption), even though the absorption of waves typically does not depend on their intensity (linear absorption).

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5 0
1 year ago
________ describes the total sediment load transported by a stream.
Taya2010 [7]
That is called the capacity.
5 0
3 years ago
When an electron is displaced in a semiconductor, the hole that's left behind is
morpeh [17]

Answer:

A. attracted to the negative terminal of the voltage source.

Explanation:

When an electron is displaced in a semiconductor, the hole that's left behind is

A. attracted to the negative terminal of the voltage source.

The electron leaving leaves a net + charge, which is attracted to the negative terminal.

8 0
2 years ago
A circular ring with area 4.45 cm2 is carrying a current of 13.5 A. The ring, initially at rest, is immersed in a region of unif
Gwar [14]

Answer:

a) ( 0.0015139 i^ + 0.0020185 j^ + 0.00060556 k^ ) N.m

b) ΔU = -0.000747871 J

c)  w = 47.97 rad / s

Explanation:

Given:-

- The area of the circular ring, A = 4.45 cm^2

- The current carried by circular ring, I = 13.5 Amps

- The magnetic field strength, vec ( B ) = (1.05×10−2T).(12i^+3j^−4k^)

- The magnetic moment initial orientation, vec ( μi ) = μ.(−0.8i^+0.6j^)  

- The magnetic moment final orientation, vec ( μf ) = -μ k^

- The inertia of ring, T = 6.50×10^−7 kg⋅m2

Solution:-

- First we will determine the magnitude of magnetic moment ( μ ) from the following relation:

                    μ = N*I*A

Where,

           N: The number of turns

           I : Current in coil

           A: the cross sectional area of coil

- Use the given values and determine the magnitude ( μ ) for a single coil i.e ( N = 1 ):

                    μ = 1*( 13.5 ) * ( 4.45 / 100^2 )

                    μ = 0.0060075 A-m^2

- From definition the torque on the ring is the determined from cross product of the magnetic moment vec ( μ ) and magnetic field strength vec ( B ). The torque on the ring in initial position:

             vec ( τi ) = vec ( μi ) x vec ( B )

              = 0.0060075*( -0.8 i^ + 0.6 j^ ) x 0.0105*( 12 i^ + 3 j^ -4 k^ )

              = ( -0.004806 i^ + 0.0036045 j^ ) x ( 0.126 i^ + 0.0315 j^ -0.042 k^ )

- Perform cross product:

          \left[\begin{array}{ccc}i&j&k\\-0.004806&0.0036045&0\\0.126&0.0315&-0.042\end{array}\right]  = \left[\begin{array}{ccc}-0.00015139\\-0.00020185\\-0.00060556\end{array}\right] \\\\

- The initial torque ( τi ) is written as follows:

           vec ( τi ) = ( 0.0015139 i^ + 0.0020185 j^ + 0.00060556 k^ )

           

- The magnetic potential energy ( U ) is the dot product of magnetic moment vec ( μ ) and magnetic field strength vec ( B ):

- The initial potential energy stored in the circular ring ( Ui ) is:

          Ui = - vec ( μi ) . vec ( B )

          Ui =- ( -0.004806 i^ + 0.0036045 j^ ) . ( 0.126 i^ + 0.0315 j^ -0.042 k^ )

          Ui = -[( -0.004806*0.126 ) + ( 0.0036045*0.0315 ) + ( 0*-0.042 )]

          Ui = - [(-0.000605556 + 0.00011)]

          Ui = 0.000495556 J

- The final potential energy stored in the circular ring ( Uf ) is determined in the similar manner after the ring is rotated by 90 degrees with a new magnetic moment orientation ( μf ) :

          Uf = - vec ( μf ) . vec ( B )

          Uf = - ( -0.0060075 k^ ) . ( 0.126 i^ + 0.0315 j^ -0.042 k^ )

          Uf = - [( 0*0.126 ) + ( 0*0.0315 ) + ( -0.0060075*-0.042 ) ]

          Uf = -0.000252315 J

- The decrease in magnetic potential energy of the ring is arithmetically determined:

          ΔU = Uf - Ui

          ΔU = -0.000252315 - 0.000495556  

          ΔU = -0.000747871 J

Answer: There was a decrease of ΔU = -0.000747871 J of potential energy stored in the ring.

- We will consider the system to be isolated from any fictitious forces and gravitational effects are negligible on the current carrying ring.

- The conservation of magnetic potential ( U ) energy in the form of Kinetic energy ( Ek ) is valid for the given application:

                Ui + Eki = Uf + Ekf

Where,

             Eki : The initial kinetic energy ( initially at rest ) = 0

             Ekf : The final kinetic energy at second position

- The loss in potential energy stored is due to the conversion of potential energy into rotational kinetic energy of current carrying ring.    

               -ΔU = Ekf

                0.5*T*w^2 = -ΔU

                w^2 = -ΔU*2 / T

Where,

                w: The angular speed at second position

               w = √(0.000747871*2 / 6.50×10^−7)

              w = 47.97 rad / s

6 0
3 years ago
IF YOU CAN TRY TO ANSER THIS AS FAST AS YOU CAN THANKYOU. Explain the relationship between physical activity, fitness, health, a
Rom4ik [11]

Answer:When losing weight, more physical activity increases the number of calories your body uses for energy or “burns off.” The burning of calories through physical activity, combined with reducing the number of calories you eat, creates a “calorie deficit” that results in weight loss.

Most weight loss occurs because of decreased caloric intake. However, evidence shows the only way to maintain weight loss is to be engaged in regular physical activity.

Most importantly, physical activity reduces risks of cardiovascular disease and diabetes beyond that produced by weight reduction alone.

Physical activity also helps to–

Maintain weight.

Reduce high blood pressure.

Reduce risk for type 2 diabetes, heart attack, stroke, and several forms of cancer.

Reduce arthritis pain and associated disability.

Reduce risk for osteoporosis and falls.

Reduce symptoms of depression and anxiety.

Top of Page

How much physical activity do I need?

Photo: Women exercising in a swimming pool

When it comes to weight management, people vary greatly in how much physical activity they need. Here are some guidelines to follow:

To maintain your weight: Work your way up to 150 minutes of moderate-intensity aerobic activity, 75 minutes of vigorous-intensity aerobic activity, or an equivalent mix of the two each week. Strong scientific evidence shows that physical activity can help you maintain your weight over time. However, the exact amount of physical activity needed to do this is not clear since it varies greatly from person to person. It’s possible that you may need to do more than the equivalent of 150 minutes of moderate-intensity activity a week to maintain your weight.

To lose weight and keep it off: You will need a high amount of physical activity unless you also adjust your diet and reduce the amount of calories you’re eating and drinking. Getting to and staying at a healthy weight requires both regular physical activity and a healthy eating plan.

Explanation:

3 0
3 years ago
Read 2 more answers
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