The maximum efficiency of a heat engine operating between 2 degrees c and 200 degrees c will be about:

A cat is sleeping on the floor in the middle of a 3.0-m-wide room when a barking dog enters with a speed of 1.50 m/s. as the dog

kondor19780726 [428]

Good morning.

Lets make the movement function for the dog and cat.

The cat has a start position of1.5 m(the middle of the room), with an initial speed of 0 and acceleration of 0.85 m/s².

The dog has a start position of 0, an initial speed of 1.5 m/s and acceleration of -0.1 m/s².

Cat:

$\mathsf{X = X_0+V_0t + \dfrac{at^2}{2}}\\ \\ \mathsf{X = 1.5 + \dfrac{0.85t^2}{2}}\\ \\ \\ \mathsf{X_c = 1.5 + 0.425t^2}$

Dog:

$\mathsf{X_d= 1.5t - 0.05t^2}$

Let's see if the dog reach the cat. Physically, it means $\mathsf{X_d = X_c}$

$\mathsf{1.5t - 0.05t^2 = 1.5 + 0.425t^2}\\ \\ \mathsf{0.425t^2 + 0.05t^2 - 1.5t + 1.5 = 0}\\ \\ \mathsf{0.475t^2 - 1.5t + 1.5=0}$

Now we solve for t:

$\mathsf{\Delta = (-1.5)^2 - 4\cdot0.475\cdot1.5}\\ \\ \mathsf{\Delta = 2.25-2.85=-0.6 \ \textless \ 0}$

We have a negative Delta. Therefore, there is no instant t when the dog reaches the cat.

6 0

2 years ago

A mercury atom in the ground state absorbs 20.00 electronvolts of energy and is ionized by losing an electron. How much kinetic

sukhopar [10]

We are given a mercury atom in the ground state which absorbs 20 eV of energy. It is then ionized by losing an electron. We need to calculate the kinetic energy that the electron has after ionization.

The initial energy is 20 eV = 20 J/C
The electron charge is = 1.60217662 × 10-19 coulombs

To determine the kinetic energy, we can use this equation:

KE = 20 Joules / Coulombs * 1.60217662 × 10-19 coulombs
KE = 1.25x10^20 Joules

Therefore, the amount of kinetic energy that the electron has after ionization is 1.25x10^20 Joules or 1.25x10^17 kJ.

8 0

2 years ago

Which of the following substances will show the smallest change in temperature when equal amounts of energy are absorbed?

SSSSS [86.1K]

It would be water because if you freeze it than you will still be able to see it and if you boil it than you will be able to see it disappear.

3 0

2 years ago

Read 2 more answers

The current supplied by a battery slowly decreases as the battery runs down. Suppose that the current as a function of time is:

ludmilkaskok [199]

Answer: 8.1 x 10^24

Explanation:

I(t) = (0.6 A) e^(-t/6 hr)

I'll leave out units for neatness: I(t) = 0.6e^(-t/6)

If t is in seconds then since 1hr = 3600s: I(t) = 0.6e^(-t/(6 x 3600) ).

For neatness let k = 1/(6x3600) = 4.63x10^-5, then:

I(t) = 0.6e^(-kt)

Providing t is in seconds, total charge Q in coulombs is

Q= ∫ I(t).dt evaluated from t=0 to t=∞.

Q = ∫(0.6e^(-kt)

= (0.6/-k)e^(-kt) evaluated from t=0 to t=∞.

= -(0.6/k)[e^-∞ - e^-0]

= -0.6/k[0 - 1]

= 0.6/k

= 0.6/(4.63x10^-5)

= 12958 C

Since the magnitude of the charge on an electron = 1.6x10⁻¹⁹ C, the number of electrons is 12958/(1.6x10^-19) = 8.1x10^24 to two significant figures.

5 0

2 years ago

Which statement best explains why hydrogen’s atomic number is equal to its mass?(1 point)

igor_vitrenko [27]

Answer:

Hydrogen has one electron and one proton

3 0

1 year ago