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pav-90 [236]
4 years ago
7

How does the law of conservation of energy apply to machinesBased on the law of conservation of energy, how can we reasonably im

prove a machine’s ability to do work?
Physics
1 answer:
SIZIF [17.4K]4 years ago
8 0

Answer:

According,to the law of conservation of energy,the amount of energy in a closed system always stay constant. ... So,the amount of work output and other transformed energy is equal to the amount of energy inputs. • In this way,the conservation of energy is fulfilled by the machines.

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A balloon filled with helium gas at 20°C occupies 4.91 L at 1.00 atm. The balloon is immersed in liquid nitrogen at -196°C, whil
Marizza181 [45]

Answer:

V = 0.248 L

Explanation:

To do this, use the following equation:

P1*V1/T1 = P2*V2/T2

This equation is used to find a relation between two differents conditions of a same gas, which is this case. From this equation we can solve for V2.

Solving for V2:

V2 = P1*V1*T2/T1*P2

Temperature must be at Kelvin, so, we have to sum the temperature 273 to convert it in K.

Replacing the data we have:

V2 = 1 * 4.91 * (-196+273) / 5.2 * (20+273)

V2 = 378.07 / 1523.6

V2 = 0.248 L

7 0
4 years ago
What is the atomic number of an atom?
Sever21 [200]

Answer:

B, the number of protons.

Explanation:

It is the number of protons found in the nucleus of the atom.

4 0
3 years ago
If the velocity of a pitched ball has a magnitude of 44.5 m/s and the batted ball's velocity is 55.5 m/s in the opposite directi
Lelu [443]

Answer:

ΔP = 14.5 Ns

I = 14.5 Ns

ΔF = 5.8 x 10³ N = 5.8 KN

Explanation:

The mass of the ball is given as 0.145 kg in the complete question. So, the change in momentum will be:

ΔP = mv₂ - mv₁

ΔP = m(v₂ - v₁)

where,

ΔP = Change in Momentum = ?

m = mass of ball = 0.145 kg

v₂ = velocity of batted ball = 55.5 m/s

v₁ = velocity of pitched ball = - 44.5 m/s (due to opposite direction)

Therefore,

ΔP = (0.145 kg)(55.5 m/s + 44.5 m/s)

<u>ΔP = 14.5 Ns</u>

The impulse applied to a body is equal to the change in its momentum. Therefore,

Impulse = I = ΔP

<u>I = 14.5 Ns</u>

the average force can be found as:

I = ΔF*t

ΔF = I/t

where,

ΔF = Average Force = ?

t = time of contact = 2.5 ms = 2.5 x 10⁻³ s

Therefore,

ΔF = 14.5 N.s/(2.5 x 10⁻³ s)

<u>ΔF = 5.8 x 10³ N = 5.8 KN</u>

4 0
3 years ago
When light of wavelength 240 nm falls on a cobalt surface, electrons having a maximum kinetic energy of 0.17 eV are emitted. Fin
dusya [7]

Answer:

(a) 5.04 eV (B) 248.14 nm (c) 1.21\times 10^{15}Hz

Explanation:

We have given Wavelength of the light  \lambda = 240 nm

According to plank's rule ,energy of light

E = h\nu = \frac{hc}{}\lambda

E = h\nu = \frac{6.67\times 10^{-34} J.s\times 3\times 10^{8}m/s}{ 240\times 10^{-9} m\times 1.6\times 10^{-19}J/eV}= 5.21 eV

Maximum KE of emitted electron i= 0.17 eV

Part( A) Using Einstien's equation

E = KE_{max}+\Phi _{0}, here \Phi _0 is work function.

\Phi _{0}=E - KE_{max}= 5.21 eV-0.17 eV = 5.04 eV

Part( B) We have to find cutoff wavelength

\Phi _{0} = \frac{hc}{\lambda_{cuttoff}}

\lambda_{cuttoff}= \frac{hc}{\Phi _{0} }

\lambda_{cuttoff}= \frac{6.67\times 10^{-34} J.s\times 3\times 10^{8}m/s}{5.04 eV\times 1.6\times 10^{-19}J/eV }=248.14 nm

Part (C) In this part we have to find the cutoff frequency

\nu = \frac{c}{\lambda_{cuttoff}}= \frac{3\times 10^{8}m/s}{248.14 \times 10^{-19} m }= 1.21\times 10^{15} Hz

5 0
3 years ago
Write whether true or false...
elixir [45]

Answer:

a --> true, b --> false, c --> true, d -->false

Explanation:

a) since it stays floating the gravity force and the upqards push is the same

b) if it's balanced the rocket won't move from the ground, the force of the rocket, has to exceed the force of gravity

c) since it's going in a diretion the force of gravity is exceeding the force pushing it up

d) since that are speeding up at a rate, meaning growing, the force is unbalanced.

8 0
3 years ago
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