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2 years ago

9

Which of the following is not a potential sign of chemical change? a. release of gas c. change of color b. evaporation of water

d. production of gas Please select the best answer from the choices provided A B C D

1 answer:

vitfil [10]2 years ago

5 0

B is the answer. because it is a physical change

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A concrete slab of mass 400 kg accelerates down a concrete slope inclined at 35°. The kinetic between the slab and slope is 0.60

belka [17]

I got you

Explanation:

normal force = 400 g cos 35

friction force up slope = .6 (400 g) cos 35

weight component down slope = 400 g sin 35

400 a = 400 g sin 35 - .6 (400 g cos 35)

a = g (sin 35 - .6 cos 35) = .082 g

I hope this helps you

8 0

2 years ago

Laser transmissions travel at a higher speed than the radio waves true or false

uranmaximum [27]

<span>False. Laser transmissions and radio waves are both forms of electromagnetic radiation. Both travel at approximately 3.00 x 10^8 meters per second. This is the case because wavelength and frequency are directly proportional to this value. Although laser light has a shorter wavelength than radio waves, it will travel at the same speed because the frequency will be greater.</span>

6 0

3 years ago

how do i write this to where it is true? in the blue is a statement and the attached piece is false so i have to make it true an

OlgaM077 [116]

Answer:

cross out the false piece in blue and write the true piece in red

4 0

3 years ago

A coil with an inductance of 2.3 H and a resistance of 14 Ω is suddenly connected to an ideal battery with ε = 100 V. At 0.13 s

klemol [59]

Given Information:

Resistance = R = 14 Ω

Inductance = L = 2.3 H

voltage = V = 100 V

time = t = 0.13 s

Required Information:

(a) energy is being stored in the magnetic field

(b) thermal energy is appearing in the resistance

(c) energy is being delivered by the battery?

Answer:

(a) energy is being stored in the magnetic field ≈ 219 watts

(b) thermal energy is appearing in the resistance ≈ 267 watts

(c) energy is being delivered by the battery ≈ 481 watts

Explanation:

The energy stored in the inductor is given by

$U = \frac{1}{2} Li^{2}$

The rate at which the energy is being stored in the inductor is given by

$\frac{dU}{dt} = Li\frac{di}{dt} \: \: \: \: eq. 1$

The current through the RL circuit is given by

$i = \frac{V}{R} (1-e^{-\frac{t}{ \tau} })$

Where τ is the the time constant and is given by

$\tau = \frac{L}{R}\\ \tau = \frac{2.3}{14}\\ \tau = 0.16$

$i = \frac{110}{14} (1-e^{-\frac{t}{ 0.16} })\\i = 7.86(1-e^{-6.25t})\\\frac{di}{dt} = 49.125e^{-6.25t}$

Therefore, eq. 1 becomes

$\frac{dU}{dt} = (2.3)(7.86(1-e^{-6.25t}))(49.125e^{-6.25t})$

At t = 0.13 seconds

$\frac{dU}{dt} = (2.3) (4.37) (21.8)\\\frac{dU}{dt} = 219.11 \: watts$

(b) thermal energy is appearing in the resistance

The thermal energy is given by

$P = i^{2}R\\P = (7.86(1-e^{-6.25t}))^{2} \cdot 14\\P = (4.37)^{2}\cdot 14\\P = 267.35 \: watts$

(c) energy is being delivered by the battery?

The energy delivered by battery is

$P = Vi\\P = 110\cdot 4.37\\P = 481 \: watts$

4 0

3 years ago

How high can a body vertically thrown with a speed of 40m/s raise after 3 sec (neglecting air

Tcecarenko [31]

y = 75.9 m

Explanation:

y = -(1/2)gt^2 + v0yt + y0

If we put the origin of our coordinate system at the point where a body is launched, then y0 = 0.

y = -(1/2)(9.8 m/s^2)(3 s)^2 + (40 m/s)(3 s)

= -44.1 m + 120 m

= 75.9

5 0

2 years ago