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3 years ago

A 2kg mass moving at 1 m/s has a kinetic energy equal to...?

Physics

1 answer:

Nookie1986 [14]3 years ago

5 0

Answer:

kinetic energy = 1/2mv2

= 1/2 x 2 x 3^2

= 9J

Explanation:

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3 years ago

An electric heater used to boil small amounts of water consists of a 15-Ω coil that is immersed directly in the water. It operat

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Answer:

t = 1120 seconds

Explanation:

Law of Conservation of Energy: It states that energy can neither be created or destroyed but it can be transformed from one form to another

The heater converts electric energy to heat energy.

According to the law of conservation of Energy,

Heat supplied by the heater = heat gained by the water.

Heat supplied by the heater = (V²/R)t, Where V = voltage, R = Resistance, t = Time.

Heat gained by the water = cm(θ₂ -θ₁)

Where c = specific heat capacity of water, m = mass of water, θ₂= final temperature of water, θ₁= initial temperature of water.

∴ (V²/R)t = cm(θ₂ -θ₁)

Making t the subject of the equation,

t = cm(θ₂ -θ₁) ×R/V²

Where c= 4200 Jkg/K, m=0.80 kg, R = 15 Ω, V = 60 V, θ₁= 20°C, θ₂ = the normal boiling point of water = 100°C

∴ t = (4200×0.8)(100 -20)×15/60²

t = (3360×80×15)/3600

t = 4032000/3600 = 1120 seconds

∴ The time required by the heater to raise the temperature of water to normal boiling point is 1120 seconds.

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3 years ago

Variations in the resistivity of blood can give valuable clues about changes in various properties of the blood. Suppose a medic

Elena-2011 [213]

Answer:

1.1 x 10^9 ohm metre

Explanation:

diameter = 1.5 mm

length, l = 5 cm

Potential difference, V = 9 V

current, i = 230 micro Ampere = 230 x 10^-6 A

radius, r = diameter / 2 = 1.5 / 2 = 0.75 x 10^-3 m

Let the resistivity is ρ.

Area of crossection

A = πr² = 3.14 x 0.75 x 0.75 x 10^-6 = 1.766 x 10^-6 m^2

Use Ohm's law to find the value of resistance

V = i x R

9 = 230 x 10^-6 x R

R = 39130.4 ohm

Use the formula for the resistance

$R=\rho \frac{l}{A}$

$\rho =\frac{RA}{l}$

$\rho =\frac{39130.4\times 0.05}{1.766\times 10^{-6}}$

ρ = 1.1 x 10^9 ohm metre

Explanation:

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3 years ago

The wavelength of green light is about the size of an atom. (T/F)

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Explanation:

The wavelength of green light is about 500 nanometers, or two thousandths of a millimeter. The typical wavelength of a microwave oven is about 12 centimeters, which is larger than a baseball.

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4 years ago

A 5kg book rests on a table. How much force is it exerting on the table?

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Answer:

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Explanation:

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