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3 years ago

A light bulb is left on for an hour and has a power of 0.1KW. How much did it cost?

1 answer:

3 0

(0.1 KW) x (1 hour) = 1.0 kWh of energy

Cost =
<em>(1.0) x (cost of 1 kWh from that utility company in that neighborhood).</em>

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A flat uniform circular disk (radius = 2.30 m, mass = 1.00 ✕ 102 kg) is initially stationary. The disk is free to rotate in the

Vadim26 [7]

The resulting angular speed = 0.6 rad / s.

<u>Explanation:</u>

Here there is no external torque acting on the system thus we can apply the law of conservation of angular momentum

Angular momentum of the man = Iω

Where I = Inertia of the man about the axis of rotation

or I = M r 2

I = 50 * 1.25*1.25 = 78.125

w = Angular velocity of the man, that can be calculated as follows

Tangential velocity of man = v = 2m/s

So time taken to describe this circle is t = (2*pi* r) / v

Now angle described in 1 revolution θ = 2*pi radians

This angle is subtended in time t = (2*pi* r) / v

Thus angular speed = w = θ/t = 2*pi* ( v/ 2π r) = v/r = 2.70 / 1.25 = 2.16 rad/s

So angular momentum of man = Iw = 78.125 * 2.16 = 168.75.

To conserve the angular momentum before and after,

Angular momentum of disk = angular momentum of the man

i.e. Iw of disk = 168.75

disk of I = (disk of M*R^2) / 2

= (1.00 * 102 * 2.30 * 2.30) / 2

= 269.79

Thus 269.79 of disk of w = 168.75

Resulting angular speed of disk = 168.75 / 269.79 = 0.6 ras / s

7 0

2 years ago

Which is an advantage of storing data digitally?

ra1l [238]

Answer:

Explanation:

Because I said so

5 0

2 years ago

Read 2 more answers

Consider a spherical volume of space that is large enough to be considered homogeneous. Also consider a particle on the surface

LenKa [72]

Answer:

Option A applies.

A. Greater than its escape speed from the mass within the volume

Explanation:

Here it is mentioned that the spherical volume is large enough for the space to be considered as homogeneous. Also, the pressure within the volume is negligible, so that will not result into the re collapse of the Universe. Now as per our knowing, Hubble's Law relates the average speed of the particle to the distance R between the Earth and the particle. So, if the particle's speed is greater than it's escape speed from the mass within the volume, then the Universe is bound to re collapse back again. Option A applies.

3 0

3 years ago

The brakes on a bicycle apply 95 N of force to the wheels. When the

Veronika [31]

Answer:

idk

Explanation:

idk

6 0

2 years ago

Assume you need to design a hydronic system that can deliver 80,000 Btu/hr. What flow rate of water is required if the temperatu

PolarNik [594]

Answer:

At 10°F change in temperature

Mass flowrate = 1.01 kg/s = 2.227 lbm/s

Volumetric flowrate = 1010 m³/s = 35667.8 ft³/s

At 20°F change in temperature

Mass flowrate = 0.505 kg/s = 1.113 lbm/s

Volumetric flowrate = 505 m³/s = 17833.9 ft³/s

Explanation:

80000 btu/hr = 23445.7 W

P = ṁc(ΔT)

ṁ = MASS flowrate

c = specific heat capacity of water = 4182 J/kg.K,

ΔT = change in temperature = 10°F

To convert, a change of 18°F is equal to a change of 10°C

A change of 10°F = 10×10/18 = 5.556°C = 5.556K

P = ṁc(ΔT)

23445.7 = ṁ(4182 × 5.556)

ṁ = 23445.7/(4182 × 5.556)

ṁ = 1.01 kg/s = 2.227 lbm/s

In volumetric flow rate, Q = density × mass flowrate = 1000 × 1.01 = 1010 m³/s = 35667.8 ft³/s

For a change of 20°F,

ΔT = change in temperature = 20°F

To convert, a change of 18°F is equal to a change of 10°C

A change of 20°F = 20×10/18 = 11.1111°C = 11.111K

P = ṁc(ΔT)

23445.7 = ṁ(4182 × 11.111)

ṁ = 23445.7/(4182 × 11.111)

ṁ = 0.505 kg/s = 1.113 lbm/s

In volumetric flow rate, Q = density × mass flowrate = 1000 × 0.505 = 505 m³/s = 17833.9 ft³/s

Hope this Helps!!!

4 0

3 years ago