A girl jogs around a horizontal circle with a constant speed. She travels one fourth of a revolution, a distance of 25 m along the circumference of the circle, in 5.0 s. The magnitude of her acceleration is

Answer:

6.3N

Explanation:

Guessed it right on castle learning

Answer:

6.3 N

Explanation:

F=kx

F=(25N/m)(0.25m)

6.3 N

Answer:

The answer is below

Explanation:

Let a be the initial velocity of motorcycle A and b be the initial velocity of motorcycle B.

After 5.68 seconds, both motorcycle had the same velocity (v), therefore for motorcycle A:

(a - v) / 5.68 = 3.87

a - v = 21.9816

v = a - 21.9816

For motorcycle B:

(b - v) / 5.68 = 18.2

b - v = 103.376

v = b - 103.376

Therefore:

a - 21.9816 = b - 103.376

b - a = -21.9816 + 103.376

b - a = 81.3944

a) The difference between their speeds at the beginning was 81.3944 m/s

b) Since b - a = 81.3944. This means that the initial velocity of motorcycle B is greater than that of motorcycle A by 81.3944 m/s.

Therefore motorcycle B was moving faster

Answer:

C. The star is receding from you with the speed of 3000 km/s

Explanation:

To get this answer we use the doppler effect equation . The formula for a receding emissor is given in the attachment.

We solve for V

V = 3x10⁶m/s

V = 3000km/s

We have the wavelength to be shifting towards red. Therefore we conclude that it is receding. We say the star is receding with speed of 3000km/s towards you.

Thank you!

Answer:

If the forces are balanced, the resultant force is zero. If the forces on an object are unbalanced, this is what happens: a stationary object starts to move in the direction of the resultant force. a moving object changes speed and/or direction in the direction of the resultant force.

Explanation:

Answer:

Explanation:

The box is moving with constant velocity so acceleration of box is zero . That means net force on the box is zero .

The weight component acting on box parallel to incline plane

= mg sin 30⁰ = 20 x 9.8 x sin 30 = 98 N

This force is acting down the plane , hence to make the net force zero acting on box , force exerted by person will also be 98 N up the incline .

Force exerted by person = 98 N

distance travelled in 5 s

= velocity x time

= 2 x 5 = 10 m

Work done by person

= 98 x 10

= 980 J .

Answer:

a) 36°

b) 0.109 kg

Explanation:

Heat flows from brass to copper with the brass having its temperature

Length of brass = 0.4

Length of copper = 0.8

Temperature of = 36.15

See attachment for calculation

The temperature at the joint is 36.15°C

The amount of ice melted is 1.086 kg

The rate of transfer of thermal energy,

   H = Q/t = KAΔT/L

  where, K is the thermal conductivity of the substance, A is cross-sectional area, ΔT is temperature difference at the ends and L is the length

As given in the question,

  the length of the brass section   [tex]L_{1}[/tex] = 0.4 m

  it's thermal conductivity      [tex]K_{b}[/tex] = 109 J[tex]s^{-1}m^{-1}K^{-1}[/tex]

  the temperature at the brass end  [tex]T_{1}[/tex] = 373K

  the length of the copper section [tex]L_{2}[/tex] = 0.8 m

  it's thermal conductivity      [tex]K_{c}[/tex] = 385 J[tex]s^{-1}m^{-1}K^{-1}[/tex]

  the temperature at the brass end  [tex]T_{1}[/tex] = 273K

 cross-sectional area of both the substance is same A = 0.007 [tex]m^{2}[/tex]

  Let the temperature at the joint be T

The rate of heat flow must be constant across the whole length of the setup.

Hence at the joint,

   [tex]\frac{K_{b}A(T_{1}-T) }{L_{1} } =\frac{K_{c}A(T-T_{2}) }{L_{2} }[/tex]

⇒ [tex]\frac{ 109*A*(373-T)}{0.4} =\frac{385*A(T-273)}{0.8}[/tex] ⇒ T=309.15 K

⇒ T = 36.15°C is the temperature at the joint.

Now we have to calculate the equivalent thermal conductivity K of the setup in order to calculate the amount of heat transfer.

considering equivalent thermal conductivity K throughout the setup we can form the following equation to calculate its value

   [tex]\frac{KA(T_{1}-T_{2} ) }{L_{1}+L_{2} } =\frac{K_{c}A(T-T_{2}) }{L_{2} }[/tex]

   ⇒   [tex]\frac{ K*A*(100)}{1.2} =\frac{385*A(36.15)}{0.8}[/tex]

   ⇒  K = 208.76 J[tex]s^{-1}m^{-1}K^{-1}[/tex]

the amount of heat transferred at the copper end in ice-water mixture in 5 minutes(300 seconds) :

        Q = [tex]\frac{KA(T_{1}-T_{2} ) }{L_{1}+L_{2} }[/tex] × t =  [tex]\frac{208.76*0.007*100}{1.2}[/tex] × 300 = 36533 J

        latent heat of fusion of ice [tex]L_{f}[/tex] = 33600 J/kg

         [tex]Q=mL_{f}[/tex]

         [tex]m=\frac{Q}{L_{f} }[/tex]

         [tex]m=\frac{36533}{33600}[/tex] ⇒ m = 1.086 kg of ice is melted in 5 minutes

Learn more about heat transfer:

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Answer:

13.37 rev/min

Explanation:

acceleration due to gravity (g) = 9.8 m/s², centripetal acceleration ([tex]a_c[/tex]) = 1.8 * g = 1.8 * 9.8 m/s² = 17.64 m/s².

r = 9 m

Centripetal acceleration ([tex]a_c[/tex]) is given by:

[tex]a_c=\frac{v^2}{r} \\\\v=\sqrt{a_c*r} \\\\v=\sqrt{17.64\ m/s^2*9\ m}\\\\v=12.6\ m/s[/tex]

The velocity (v) is given by:

v = ωr;  where ω is the angular velocity

Hence:

ω = v/r = 12.6 / 9

ω = 1.4 rad/s

ω = 2πN

N = ω/2π = 1.4 / 2π

N = 0.2228 rev/s

N = 13.37 rev/min

Answer:

c, its axis is tilted

maybe

As it works its way around the sun, its tilted axis exposes different parts of earth.

C would be it because the roation of Earth on its axis doesn't have anything to do with the exposer of the revolution on its axis

Answer:

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Answer:

Uniform area charge density rho is needed is 3.82*10^-8 C.m^-2

Explanation:

See the attached files.

To find the rho, I used Gauss law for cylindrical shell which is equation 1 and Gauss law for the rod which is equation 4.

Note that in equation 4, Lamda is the charge per length while L is the length if the rod. Also R is the radius of the shell.

The final answer is 3.82*10^-8 C.m^-2 which is the uniform area charge density rho is needed.

It's c I think ( 4 , 2 , 6 , )

Answer:

If it accelerates at 20 m/s2 for a period of 22 seconds, what is its final velocity? ... How fast is the ball falling after 5 seconds? v = v0 + gt v = 0 + 10(5) v = 50 m/s. 4. ... + ½ 2.5(15)2 x = 281 m. 5. What is the total displacement of the car in question 2? ... 8. A base jumper falls until he reaches a speed of 200 m/s

Explanation:

Answer:

h1/h2 = [tex]\frac{2R^2}{3R^2 + h^2}[/tex]

Explanation:

Using two rolls of tissue paper : One roll dropped normally while the other drops as some holds onto a sheet of the toilet paper ( I.e. the tissue paper drops rotating about its axis )

Determine the ratio of heights  h1/h2

mass of tissues = same

radius of tissues = same

h1 = height of tissue 1

h2 = height of tissue 2

For the first tissue ( Tissue that dropped manually )

potential energy = kinetic energy

mgh = 1/2 mv^2  

therefore the final velocity ( v^2 ) = 2gH  ----- ( 1 )

second tissue ( Tissue that dropped while rotating )

gh = [tex]\frac{v^2}{u}[/tex] ( 3 + [tex]\frac{u^2}{R^2}[/tex] ) ------ ( 2 )

To determine the ratio of heights we will equate equations 1 and 2

hence :

gh = [tex]\frac{2gH}{u}[/tex] ( 3 + [tex]\frac{u^2}{R^2}[/tex] )

∴ h1/h2 = [tex]\frac{2R^2}{3R^2 + h^2}[/tex]

Answer:

θ = 90º

Explanation:

The velocity is given by

          v = [tex]\frac{dr}{dt}[/tex]

calculate

          v = 3 i ^ + √2 j ^ + 2t k ^

acceleration is defined by

         a = dv / dt

         a = 2 k ^

one way to find the angle is with the dot product

         v. a = | v | | a | cos θ

         cos θ= v.a / | v | | a |

Let's look for the value of each term

       v. a = 4 t

        | v | = [tex]\sqrt{3^2 + 2 + (2t)^2 }[/tex] = [tex]\sqrt{ 11 + 4t^2}[/tex]

        | a | = 2

they ask us for the angle for time t = 0

         v. a = 0

        | v | = √11 = 3.317

we substitute

        cos θ = 0 /√11

        cos θ = 0

therefore the angles must be θ = 90º

Answer:

Magnitude of it's displacement = 1,000 km

Explanation:

Given:

Distance towards east = 800 km

Distance towards north = 600 km

Find:

Magnitude of it's displacement

Computation:

Magnitude of it's displacement = √800² + 600²

Magnitude of it's displacement = √640000 + 360000

Magnitude of it's displacement = √10000000

Magnitude of it's displacement = 1,000 km

Answer:

I think A

Explanation:

because I don't think a unknowned number can be a division problem

Answer:

mechanical wave

Explanation:

The sound vibrations cause waves of pressure that travel through a medium, such as air, water, wood or metal. Sound energy is a form of mechanical energy

Answer:

A mechanical waves

Explanation:

in nature include water waves, sound waves, seismic waves and internal water waves

Answer:

Explanation:

Increases. The force of gravity is distance dependent. Therefore, a smaller 'r' value will result in a larger force. Net force is proportional to the acceleration, so the planet will increase its speed.

Explanation:

You do the radius times the circumference of the earth

ok so i dont know srry5

Answer:

c. The roller coaster is in uniform circular motion

Explanation:

Since the loop is circular with radius r, and its instantaneous speed, v is always constant, and also, its centripetal acceleration, a' = v²/r.

Since the angular speed, ω = v/r does not change, the magnitude of its  tangential acceleration is zero although there is a change in its direction because the direction of its initial velocity changes. That is a" = rα and α = Δω/Δt since Δω = 0, α = 0 and a" = r(0) = 0

So, there is no tangential acceleration. Since there is no tangential acceleration, our instantaneous acceleration which is the vector sum of our centripetal acceleration and tangential acceleration is a = √(a'² + a"²) =  √(a'² + 0²) = √a'² = a' = v²/r

So, a is always v²/r.

Since the instantaneous acceleration is always (a = v²/r) constant, the motion is uniform. So, it is uniform circular motion.

The roller coaster is not in uniform circular motion, and [tex]a = \frac{v^2}{r}[/tex] is only applicable at the very top and bottom of the loop where the tangential acceleration vanishes.

The given parameters;

The motion tension on the loop at the lowest point in the circular motion is given as;

[tex]T = mg + \frac{mv^2}{r}[/tex]

The motion tension on the loop at the highest point in the circular motion is given as;

[tex]T = \frac{mv^2}{r} - mg[/tex]

This shows that circular motion is affected by;

Thus, we can that the roller coaster is not in uniform circular motion, and [tex]a = \frac{v^2}{r}[/tex] is only applicable at the very top and bottom of the loop where the tangential acceleration vanishes.

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Answer:

 v = [tex]\sqrt{\frac{y_o \ g}{2} }[/tex]

Explanation:

For this exercise we must use the projectile launch ratios, let's start by finding the time it takes to reach the bottom of the cliff, the initial vertical velocity is zero

          y = y₀ + [tex]v_{oy}[/tex] t - ½ g t²

at the bottom of the cliff y = 0 and as the body is thrown horizontally the initial vertical velocity is zero

          0 = y₀ + 0 - ½ g t²

          t = [tex]\sqrt{2y_o/g}[/tex]

this time is the same as the horizontal movement.

Let's use Newton's second law to find the acceleration on this x-axis due to the force of the air

           F = m aₓ

they tell us that force is equal to the weight of the body

           -mg = maₓ

           aₓ = -g

the sign indicates that the acceleration is to the left

we write the kinematics equation

          x = x₀ + v₀ₓ t + ½ aₓ t²

They indicate that the final position is the foot of the cliff (x = 0), when it leaves the top it is at x₀ = 0 and has a velocity v₀ₓ = v

we substitute

          0 = 0 + v t + ½ (-g) t²

          v = ½ g t

we use the drop time

          v = ½ g [tex]\sqrt{\frac{2yo}{g} }[/tex]

          v = [tex]\sqrt{\frac{y_o \ g}{2} }[/tex]

Answer:

1.875 x 10⁶ m /s .

Explanation:

Force on electron = E e where E is electric field and e is charge on electron

acceleration generated = Ee / m where m is mass of the electron .

Putting the values

acceleration generated = 5 x 1.6 x 10⁻¹⁹ / 9.1 x 10⁻³¹

= .879 x 10¹² m /s²

v² = u² + 2 as , initial velocity u = 0 , displacement s = 2 m

v² = 0 + 2 x .879 x 10¹² x 2

v = 1.875 x 10⁶ m /s .

Answer:

Covalent bonds can form between similar atoms.

Explanation:

Answer:

Current through them, voltage across them.

Explanation:

Ohm's law states that at constant temperature, the current flowing in an electrical circuit is directly proportional to the voltage applied across the two points and inversely proportional to the resistance in the electrical circuit.

Mathematically, Ohm's law is given by the formula;

[tex] V = IR[/tex]

Where;

V represents voltage measured in voltage.

I represents current measured in amperes.

R represents resistance measured in ohms.

A resistor can be defined as an electronic component that opposes the free flow of current from one point to another in an electrical circuit.

In a series circuit of two resistors, the resistors have the same current through them; in a parallel circuit of two resistors, the resistors have the same voltage across them.

Option C shows the direction of the force of the ball on the spring. The direction of the force of the ball on the spring will be downwards.

Force is defined as the push or pull applied to the body. Sometimes it is used to change the shape, size, and direction of the body.

Force is defined as the product of mass and acceleration. Its unit is Newton.

The spring is extended downward because the weight is always act downwards. The direction of the force of the ball on the spring will be downwards.

Hence, option C shows the direction of the force of the ball on the spring

To learn more about the force, refer to the link;

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Answer:

A

Explanation:

In 5 minutes, they went 10 miles at both 2, 3, and 4 checkpoints. The bus then starts to speed up.

Hope this helps!