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3 years ago

14

physical changes occur when existing bonds break and new bonds form

1 answer:

Luba_88 [7]3 years ago

6 0

<span>A physical change is any change that alters the form or appearance of a substance but does not change it into another substance
-Some of the physical properties may be altered, but the chemical composition stays the same
-Examples: Bending, Crushing, Cutting, Melting, Freezing, Boiling</span>

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How fast must a 1000 kg car be moving to have a kinetic energy of:

VMariaS [17]

Answer:

$\mathrm{(a)}\: 2\: \mathrm{m/s}\\\mathrm{(b)}\: 20\: \mathrm{m/s}\\$

Explanation:

The kinetic energy of an object is given by $KE=\frac{1}{2}mv^2$ where $m$ is the mass of the object and $v$ is the velocity of the object.

We can set up the following equations with the information given:

$\mathrm{(a)}\: 2.0\cdot 10^3=\frac{1}{2}\cdot 1000\cdot v^2, \\v=\fbox{$2\: \mathrm{m/s}$}$

For part B, we have the same equation, but kinetic energy is now $2.0\cdot 10^5$ .

Therefore:

$\mathrm{(b)}\: 2.0\cdot 10^5=\frac{1}{2}\cdot 1000\cdot v^2, \\v=\fbox{$20\: \mathrm{m/s}$}$ .

6 0

3 years ago

Light that has a wavelength of 600 nm strikes a metal surface, and a stream of electrons is ejected from the surface. If light o

Anni [7]

Answer:

The maximum kinetic energy of the electrons emitted from the surface will be greater.

Option 3 is correct.

Explanation:

Given that,

Wavelength $\lambda_{1}=600\ nm$

Wavelength $\lambda_{2}=500\ nm$

We need to calculate the energy for first wavelength

Using formula of energy

$E=hf$

$E=h\dfrac{c}{\lambda}$

Put the value into the formula

$E_{1}=6.67\times10^{-34}\times\dfrac{3\times10^{8}}{600\times10^{-9}}$

$E_{1}=3.33\times10^{-19}\ J$

We need to calculate the energy for second wavelength

Put the value into the formula

$E_{2}=6.67\times10^{-34}\times\dfrac{3\times10^{8}}{500\times10^{-9}}$

$E_{2}=4.002\times10^{-19}\ J$

So, E₂>E₁

Hence, The maximum kinetic energy of the electrons emitted from the surface will be greater.

8 0

3 years ago

Learning is to perception as ____ is to ___?

siniylev [52]

Answer:

habituation; adaptation

Explanation:

5 0

3 years ago

A person slaps her leg with her hand, bringing her hand to rest in 2.50 milliseconds from an initial speed of 4.00 m/s.

gtnhenbr [62]

Answer:

(a) 2400N

(b) Yes

Explanation:

(a) Mass (m) = 1.5kg, initial speed (v) = 4m/s, time (t) = 2.5milliseconds = 2.5/1000 = 0.0025seconds

F = mv/t = (1.5×4)/0.0025 = 6/0.0025 = 2400N

(b) The force would be different because the mass of the two hands and forearms is 3kg (2 × 1.5kg = 3kg)

4 0

3 years ago

Can someone help me asap, please?

Anon25 [30]

Answer:

kinetic energy, form of energy that an object or a particle has by reason of its motion.

potential energy, stored energy that depends upon the relative position of various parts of a system

6 0

2 years ago