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stepan [7]
3 years ago
8

Suppose kinetic energy is 4 joules of a moving object what will happen if we increase the speed twice

Physics
1 answer:
Artyom0805 [142]3 years ago
3 0

Answer:

The kinetic energy is 16 joules.                        

Explanation:

Kinetic energy (E) is given by:

E = \frac{1}{2}mv^{2}

Where:

m: is the mass

v: is the speed

When the kinetic energy is 4 joules, the speed of the object is:

v_{1}^{2} = \frac{2E_{1}}{m} = \frac{8}{m}                         

Now, if the speed is increased twice then we have:

E_{2} = \frac{1}{2}mv_{2}^{2} = \frac{1}{2}m(2v_{1})^{2} = \frac{1}{2}m[4(\frac{8}{m})] = 16 J

Therefore, the kinetic energy is 4 times the initial value.  

I hope it helps you!                                

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A power cycle operates between hot and cold reservoirs at 1200 K and 300 K, respectively. At steady state the cycle develops a p
GenaCL600 [577]

Answer:

Explanation:

a ) Thermal efficiency = work output / heat input

= .38 MW / 1 MW = .38

OR 38%

Heat rejected at cold reservoir = heat input - work output

1 MW - .38 MW

= 0.62 MW.

b ) For reversible power output

efficiency = T₂ - T₁ / T₂   ; T₂ is temperature of hot reservoir and T₁ is temperature of cold reservoir.

= 1200 - 300 / 1200 = 900 / 1200

= .75

or 75%

rate at which heat is rejected

= 1 - .75 x 1

= .25 MW .

7 0
2 years ago
Ultraviolet light having a wavelength of 97 nm strikes a metallic surface. Electrons leave the surface with speeds up to 3.48 ×
irga5000 [103]

Answer:

<h2><em>12.45eV</em></h2>

Explanation:

Before calculating the work function, we must know the formula for calculating the kinetic energy of an electron. The kinetic energy of an electron is the taken as the difference between incident photon energy and work function of a metal.

Mathematically, KE =  hf - Ф where;

h is the Planck constant

f is the frequency = c/λ

c is the speed of light

λ is the wavelength

Ф is the work function

The formula will become KE =  hc/λ - Ф. Making the work function the subject of the formula we have;

Ф = hc/λ - KE

Ф = hc/λ - 1/2mv²

Given parameters

c = 3*10⁸m/s

λ = 97*10⁻⁹m

velocity of the electron v = 3.48*10⁵m/s

h = 6.62607015 × 10⁻³⁴

m is the mass of the electron = 9.10938356 × 10⁻³¹kg

Substituting the given parameters into the formula Ф = hc/λ - 1/2mv²

Ф =  6.63 × 10⁻³⁴*3*10⁸/97*10⁻⁹ -  1/2*9.11*10⁻³¹(3.48*10⁵)²

Ф = 0.205*10⁻¹⁷ - 4.555*10⁻³¹*12.1104*10¹⁰

Ф = 0.205*10⁻¹⁷ - 55.163*10⁻²¹

Ф = 0.205*10⁻¹⁷ - 0.0055.163*10⁻¹⁷

Ф = 0.1995*10⁻¹⁷Joules

Since 1eV = 1.60218*10⁻¹⁹J

x = 0.1995*10⁻¹⁷Joules

cross multiply

x = 0.1995*10⁻¹⁷/1.60218*10⁻¹⁹

x = 0.1245*10²

x = 12.45eV

<em>Hence the work function of the metal in eV is 12.45eV</em>

6 0
3 years ago
3. How are fossil fuels used to generate electrical energy?
Katena32 [7]
Um dia eu vou para os Estados Unidos aí nós vamos ser amigos?
5 0
3 years ago
Read 2 more answers
What happen to the bulb when it is in series connection?
coldgirl [10]
If the bulb is in series with something else, then . . .

--  The brightness of the bulb depends on the <em>other</em> device in the circuit. 

--  If the other device is designed to use <em>less power</em> than the bulb, then the
other device gets <em>more power</em> than the bulb gets.

--  If the other device is designed to use <em>more power </em>than the bulb, then the
other device gets <em>less power</em> than the bulb gets.

--  If the other device is removed from the circuit, then the bulb doesn't light at all.

This description of the often-screwy behavior of a series circuit may partly explain
why the electric service in your home is not a series circuit.




8 0
3 years ago
Read 2 more answers
A sample of gas with a volume of 750 ml exerts a pressure of 98 kpa at 30◦c. What pressure will the sample exert when it is comp
Tanzania [10]

Answer:

241 kPa

Explanation:

The ideal gas law states that:

pV=nRT

where

p is the gas pressure

V is its volume

n is the number of moles

R is the gas constant

T is the absolute temperature of the gas

We can rewrite the equation as

\frac{pV}{T}=nR

For a fixed amount of gas, n is constant, so we can write

\frac{pV}{T}=const.

Therefore, for a gas which undergoes a transformation we have

\frac{p_1 V_1}{T_1}=\frac{p_2 V_2}{T_2}

where the labels 1 and 2 refer to the initial and final conditions of the gas.

For the sample of gas in this problem we have

p_1 = 98 kPa=9.8\cdot 10^4 Pa\\V_1 = 750 mL=0.75 L=7.5\cdot 10^{-4}m^3\\T_1 = 30^{\circ}C+273=303 K\\p_2 =?\\V_2 = 250 mL=0.25 L=2.5\cdot 10^{-4} m^3\\T_2 = -25^{\circ}C+273=248 K

So we can solve the formula for p_2, the final pressure:

p_2 = \frac{p_1 V_1 T_2}{T_1 V_2}=\frac{(9.8\cdot 10^4 Pa)(7.5\cdot 10^{-4} m^3)(248 K)}{(303 K)(2.5\cdot 10^{-4} m^3)}=2.41\cdot 10^5 Pa = 241 kPa

4 0
3 years ago
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