All categories

3 years ago

How are physical and chemical changes similar?

1 answer:

5 0

<span>They are similar because the matter changes in its state...But they are also different because Physical changes have matter that remains the same substance but it is just in a different state and in chemical changes the matter changes completely... Hope this Helps ^-^</span>

You might be interested in

What is the frequency of an electromagnetic wave that has a wavelength of 4,000m?

NeTakaya

Answer:

f=75000hz

Explanation:

fλ= c

f= c/λ

f = 3.0×10^8/4000

f=75000hz

7 0

4 years ago

A person in a wheelchair exerts a force of 25 newtons to go up a ramp that is 10 meters long. The weight of the person and wheel

Natali [406]

The work output of the procedure is given as,

$W_O=wh$

Substitute the known values,

$\begin{gathered} W_O=(60\text{ N)(3 m)(}\frac{1\text{ J}}{1\text{ Nm}}) \\ =180\text{ J} \end{gathered}$

Thus, the work output is 180 J.

The work input of the procedure is,

$W_i=Fd$

Substitute the known values,

$\begin{gathered} W_i=(25\text{ N)(10 m)(}\frac{1\text{ J}}{1\text{ Nm}}) \\ =250\text{ J} \end{gathered}$

Thus, the work input is 250 J.

The efficiency of the person is given as,

$e=\frac{W_O}{W_i}$

Substitute the known values,

$\begin{gathered} e=\frac{180\text{ J}}{250\text{ J}} \\ =0.72 \end{gathered}$

Thus, the efficiency of person is 0.72 or 72%.

5 0

1 year ago

A child bounces in a harness suspended from a door frame by three elastic bands. If each elastic band stretches 0.300 m while su

WINSTONCH [101]

Answer:

The force constant for each elastic band is 77.93 N/m

Explanation:

Hooke's law of a spring or an elastic band gives the relation between elastic force (Fe) and stretching (x), the magnitude of that force is:

$F_{e}= kx$ (1)

With k, the elastic force constant. The three elastic bands support the child’s weight (W) and maintain him at rest, so by Newton’s second law for one of the elastic bands:

$\sum F=0$ (2)

$\frac{W}{3}-F_{e}=0\Rightarrow F_{e}=\frac{W}{3}$ (3)

Using (1) on (3):

$kx=\frac{W}{3}\Rightarrow k=\frac{mg}{3x}$ (4)

$k=\frac{7.15\,kg*9.81\,\frac{m}{s^{2}}}{3*0.300\,m}\simeq\mathbf{77.93\frac{N}{m}}$

8 0

3 years ago

A truck traveling at a constant speed of 28 m/s passes a more slowly moving car. The instant the truck passes the car, the car b

choli [55]

Answer:

the velocity of car when it passes the truck is u = 16.33 m/s

Explanation:

given,

constant speed of truck = 28 m/s

acceleration of car = 1.2 m/s²

passes the truck in 545 m

speed of the car when it just pass the truck = ?

time taken by the truck to travel 545 m

time = $\dfrac{distance}{speed}$

time = $\dfrac{545}{28}$

time =19.46 s

velocity of the car when it crosses the truck

$S = ut + \dfrac{1}{2}at^2$

$545= u\times 19.46 + \dfrac{1}{2} \times 1.2 \times 19.46^2$

u = 16.33 m/s

the velocity of car when it passes the truck is u = 16.33 m/s

5 0

4 years ago

HELP!<br> how did Mario Molina contribute to science?<br><br> i need like a mini paragraph:(

charle [14.2K]

Mario Molina helped to bring about the 1987 Montreal Protocol on substances that result in depletion of the Ozone Layer.

<h3>What is ozone layer?</h3>

The topmost layer of the atmosphere which protect the harmful UV rays from the Sun to reach the Earth surface.

Mario Molina has the great contribution in science field. He tried hard and succeeded in passing an international agreement to eliminate CFCs also called as Chloro Fluoro Carbons and other ozone-depleting chemicals.

These CFCs were used in jet planes which depleted the ozone layer and a hole was observed over Antarctica.

Learn more about ozone layer.

brainly.com/question/14330630

#SPJ1

7 0

3 years ago