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3 years ago

PLEASE HELP!!! PLEASE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

1 answer:

4 0

For the first one, the correct answer would be "Substance changes its form but not its molecular composition.". During a physical change (let's say cutting paper), the substance has its shape changed, but it is still itself (paper).

The second one is a bit trickier: 
Kinetic energy of a molecule is directly influenced by temperature. If there is a higher temperature it will have a higher kinetic energy which means the molecule moves at a higher velocity. This will increase the chance of particles bouncing off of each other during the chemical reaction. That explains why the rate of reaction will be higher at a higher temperature, rather than higher at a cool temperature. The correct answer would be lower at 39F.

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A student is bouncing on a trampoline. at her highest point, her feet are 65 cm above the trampoline. when she lands, the trampo

Ede4ka [16]

she is in contact with the trampoline for less than one second.

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3 years ago

Which statement is true of AC current?. Select one of the options below as your answer:. . A.. It uses a battery as a power sour

Nonamiya [84]

The answer is B. It can be converted from high to low voltage and vice versa using transformers. That is why high voltages (tens or hundreds of kilovolts) is used to efficiently transfer electricity for large distances and then converted to 110-240V.

The answer can also be derived by elimination. [A] is not right because battery provides only Direct Current (DC). [C] is not right because high voltages are used for AC (from 110V to hundreds of kilovolts). [D] is not right because as the name Alternating Current suggests, the current is alternating in its direction. [E] is not right because DC was the first type of current invented.

8 0

3 years ago

Read 2 more answers

A wave with a period of 1⁄3 second has a frequency of A. 67 Hz. B. 33 Hz. C. 300 Hz. D. 3 Hz.

Triss [41]

A wave with a period of 1⁄3 second has a frequency of D. 3 Hz. To calculate this we will use the formula that represents the correlation between a frequency (f) and a time period (T): T = 1/f. Or: f = 1/T. The unit for the time period is second "s" while the unit for frequency is Hertz "Hz" (=1/s). We know that T = 1/3 s. That means that f = 1/(1/3s) = 3 1/s = 3 Hz.

3 0

4 years ago

The small metal cylinder has a mass of 0.20 kgkg, the coefficient of static friction between the cylinder and the turntable is 0

deff fn [24]

Answer:

velocity of the metal cylinder = 0.343 m/s

Explanation:

Force putting the metal cylinder is given by

F = mv²/r

But this force will balance the frictional force between the metal cylinder and the turntable

The frictional force is given by

μN = μ × mg = 0.08 × 0.2 × 9.81 = 0.15696 N

r = 0.15 m, m = 0.2 kg,

F = mv²/r = 0.2 v²/(0.15) = 1.3333 v²

1.3333 v² = 0.15696

v² = 0.117

v = 0.343 m/s

8 0

3 years ago

An aluminum cup contains 225 g of water and a 40-g copper stirrer, all at 27Â°C. A 470-g sample of silver at an initial temperat

vagabundo [1.1K]

Answer:

Mal = 0.232 kg = 232 g

Explanation:

mass of water (Mw) = 225 g = 0.225 kg

mass of copper stirrer (Mcu) = 40 g = 0.04 kg

initial temperature of water (Tw) = 27 degrees

mass of silver (Mag) = 470 g = 0.47 kg

initial temperature of silver (Ts) = 85 degrees

final temperature of the mixture (T) = 32 degrees

find the mass of the aluminum cup (Mal)

applying the conservation of energy

((Mal.cAl) + (Mw.cW) + (Mcu.cCu))(ΔTw) = (Mag.cAg)(ΔTag)

we require the specific heat capacities of water (cW) , aluminium (cAl) , copper (cCu) and silver (cAg) which are as follows

water (cW) =4186 J/kg.K

aluminium (cAl) = 900 J/kg.K

copper (cCu) = 387 J/kg.K

silver (cAg) = 234 J/kg.K

now we can put in our values to get the mass of the Aluminium cup (Mag)

((Mal.900) + (0.225 x 4186) + (0.04 x 387))(32-27) = (0.47 x 234)(85-32)

(900 . Mal + 957.33) x 5 = 5828.94

900 .Mal + 957.33 = 1165.79

900.Mal = 1165.79 - 957.33 = 208.5

Mal = 0.232 kg = 232 g

8 0

4 years ago