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2 years ago

What does it mean when there is a physical change?

Physics

2 answers:

emmainna [20.7K]2 years ago

8 0

Answer:

D.matter has changed size,shape, or form

Explanation:

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valkas [14]2 years ago

7 0

Answer:

Chemists make a distinction between two different types of changes that they study—physical changes and chemical changes. Physical changes are changes that do not alter the identity of a substance. Chemical changes are changes that occur when one substance is turned into another substance

Explanation:

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A car of mass 2400kg moving at 20 m/s slams into a cement wall and comes to a halt?

Brut [27]

Impulse = change in momentum

The car's momentum was (mass) x (speed)

Momentum = (2400 kg) x (20 m/s)

Momentum = 48,000 km-m/s

To completely stop the car, the impulse = -48,000 km-m/s .

7 0

3 years ago

There is a species of bamboo that can grow 36 inches per day. If a plant grew at this rate and was measured at 40 inches initial

LekaFEV [45]

Answer:

It will take the plant $4\frac{4}{9}$ days or 4.44 days to grow to a height of 200 inches tall.

Explanation:

From the question, the rate at which the species of the bamboo tree grows is 36 inches per day.

To determine how long it would take a plant 40 inches tall initially to grow at this rate (that is, 36 inches per day) to a height of 200 inches.

This means we will calculate the number of days it will take the plant to grow additional 160 inches ( 200 inches - 40 inches) at this rate.

Now,

If the plant grows 36 inches in 1 day

then it will grow 160 inches in x days

x = (160 inches × 1 day) / 36 inches

x = 160 / 36

x = $4\frac{4}{9}$ days or 4.44 days

Hence, it will take the plant $4\frac{4}{9}$ days or 4.44 days to grow to a height of 200 inches tall.

8 0

2 years ago

Calculate the velocity of a wave that has a frequency of 60 Hz and wavelength of 2.0 m/s

mote1985 [20]

Answer:We have , a relation in frequency f and wavelength λ of a wave having the velocity v as ,

v=fλ ,

given f=60Hz , λ=20m ,

therefore velocity of wave , v=60×20=1200m/s

3 0

2 years ago

What is the energy in joules of a mole of photons associated with visible light of wavelength 486 nm?

ivann1987 [24]

Answer:

$2.46\cdot 10^5 J$

Explanation:

The energy of a single photon is given by:

$E=\frac{hc}{\lambda}$

where

h is the Planck constant

c is the speed of light

$\lambda$ is the wavelength

For the photon in this problem,

$\lambda=486 nm=4.86\cdot 10^{-7}m$

So, its energy is

$E_1=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{4.86\cdot 10^{-7}m}=4.09\cdot 10^{-19} J$

One mole of photons contains a number of photons equal to Avogadro number:

$N_A = 6.022\cdot 10^{23}$

So, the total energy of one mole of photons is

$E=N_A E_1 = (6.022\cdot 10^{23})(4.09\cdot 10^{-19} J)=2.46\cdot 10^5 J$

7 0

3 years ago

The power of the kettle was 2.6 kW

faltersainse [42]

Answer:

Cp = 4756 [J/kg*°C]

Explanation:

In order to calculate the specific heat of water, we must use the equation of energy for heat or heat transfer equation.

Q = m*Cp*(T_f - T_i)/t

where:

Q = heat transfer = 2.6 [kW] = 2600[W]

m = mass of the water = 0.8 [kg]

Cp = specific heat of water [J/kg*°C]

T_f = final temperature of the water = 100 [°C]

T_i = initial temperature of the water = 18 [°C]

t = time = 120 [s]

Now clearing the Cp, we have:

Cp = Q*t/(m*(T_f - T_i))

Now replacing

Cp = (2600*120)/(0.8*(100-18))

Cp = 4756 [J/kg*°C]

7 0

2 years ago