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2 years ago

How fast is a ball rolling if it contains 98 j of kinetic energy and has a mass of 4kg

Physics

1 answer:

zysi [14]2 years ago

4 0

Answer:

the ball is rolling 7m/s

Explanation:

Formula for kinetic energy: 1/2mv²

K = 1/2mv²

98 = 1/2(4)v²

98 = 2v²

49 = v²

√49 = v

7 = v

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A long, fine wire is wound into a coil with inductance 5 mH. The coil is connected across the terminals of a battery, and the cu

Effectus [21]

Answer:

Compared with the current in the first coil, the current in the second coil is unchanged.

Explanation:

All coils, inductors, chokes and transformers create a magnetic field around themselves consist of an Inductance in series with a Resistance forming an LR Series Circuit.

The steady state of current in the LR circuit is:

I= V/R (1 - e^-Rt/L)

Where I= current

R= Resistance

V= Voltage

Where R/L is the time constant.

For a conducting wire, it has a very small resistance. The time constant will be in microseconds. The current will be in a steady state after few second. The current is independent on the inductance and dependent on the resistance. The length of wire and the resistance here are the same. Therefore, the current remains unchanged.

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2 years ago

Read 2 more answers

Two astronauts (each with mass 100 kg) are drifting together through space. They are connected to each other by a rope 5 m in le

Nana76 [90]

Answer:

1000 kgm²/s, 400 J

1000 kgm²/s, 1000 J

600 J

Explanation:

m = Mass of astronauts = 100 kg

d = Diameter

r = Radius = $\frac{d}{2}$

v = Velocity of astronauts = 2 m/s

Angular momentum of the system is given by

$L=mvr+mvr\\\Rightarrow L=2mvr\\\Rightarrow L=2\times 100\times 2\times 2.5\\\Rightarrow L=1000\ kgm^2/s$

The angular momentum of the system is 1000 kgm²/s

Rotational energy is given by

$K=I\omega^2\\\Rightarrow K=\frac{1}{2}(mr^2)\left(\frac{v}{r}\right)^2\\\Rightarrow K=mv^2\\\Rightarrow K=100\times 2^2\\\Rightarrow K=400\ J$

The rotational energy of the system is 400 J

There no external toque present so the initial and final angular momentum will be equal to the initial angular momentum 1000 kgm²/s

$L_i=L_f\\\Rightarrow 2mv_ir_i=2mv_fr_f\\\Rightarrow v_f=\frac{v_ir_i}{r_f}\\\Rightarrow v_f=\frac{2\times 2.5}{0.5}\\\Rightarrow v_f=10\ m/s$

Energy

$E_2=mv_f^2\\\Rightarrow E_2=100\times 10\\\Rightarrow E_2=1000\ J$

The new energy will be 1000 J

Work done will be the change in the kinetic energy

$W=E_2-E\\\Rightarrow W=1000-400\\\Rightarrow W=600\ J$

The work done is 600 J

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2 years ago

Where is heat transferred by conduction in a lava lamp?

Semmy [17]

It is transferred by direct contact, say you touched it, you would feel the heat

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2 years ago

if researchers hit a sheet of metal with a yellow light and nothing happens, what color should the try next?

Nataliya [291]

The photoelectric emission is possible if the wavelength of the incident light is less than that of yellow light

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3 years ago

What is the distance from axis about which a uniform, balsa-wood sphere will have the same moment of inertia as does a thin-wall

andrey2020 [161]

Answer:

$D_{s}$ ≈ 2.1 R

Explanation:

The moment of inertia of the bodies can be calculated by the equation

I = ∫ r² dm

For bodies with symmetry this tabulated, the moment of inertia of the center of mass

Sphere $Is_{cm}$ = 2/5 M R²

Spherical shell $Ic_{cm}$ = 2/3 M R²

The parallel axes theorem allows us to calculate the moment of inertia with respect to different axes, without knowing the moment of inertia of the center of mass

I = $I_{cm}$ + M D²

Where M is the mass of the body and D is the distance from the center of mass to the axis of rotation

Let's start with the spherical shell, axis is along a diameter

D = 2R

Ic = $Ic_{cm}$ + M D²

Ic = 2/3 MR² + M (2R)²

Ic = M R² (2/3 + 4)

Ic = 14/3 M R²

The sphere

Is = $Is_{cm}$ + M [ $D_{s}$ ²

Is = Ic

2/5 MR² + M $D_{s}$ ² = 14/3 MR²

$D_{s}$ ² = R² (14/3 - 2/5)

$D_{s}$ = √ (R² (64/15)

$D_{s}$ = 2,066 R

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2 years ago