All categories

2 years ago

A physical change

Physics

1 answer:

Wittaler [7]2 years ago

6 0

Answer: D) occurs when water is evaporated.

Explanation:

A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.

A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.

a). iron rusts :the chemical reaction occurs by combination of iron with oxygen , thus a chemical change.

b) sugar is heated into caramel. the chemical reaction occurs by decomposition , thus a chemical change.

c) glucose is converted into energy within your cells: the chemical reaction occurs by decomposition , thus a chemical change.

d) when water is evaporated : Only the state changes and thus a physical change and cannot be reversed.

e) when propane is burned for heat: the chemical reaction as propane combines with oxygen to form carbon dioxide and water , thus a chemical change.

You might be interested in

A man pushes his child in a grocery cart. The total mass of the cart and child is 30.0 kg. If the force of friction on the cart

Ber [7]

Newton's second law states that the resultant of the forces applied to an object is equal to the product between the object's mass and its acceleration:
$\sum F = ma$
where in our problem, m is the mass the (child+cart) and a is the acceleration of the system.

We are only concerned about what it happens on the horizontal axis, so there are two forces acting on the cart+child system: the force F of the man pushing it, and the frictional force $F_f$ acting in the opposite direction. So Newton's second law can be rewritten as
$F-F_a = ma$
or
$F=ma + F_f$

since the frictional force is 15 N and we want to achieve an acceleration of $a=1.50 m/s^2$ , we can substitute these values to find what is the force the man needs:
$F=(30 kg)(1.5 m/s^2)+15 N=60 N$

8 0

2 years ago

What do radio waves and microwaves have in common?

Rom4ik [11]

All the options are wrong is there another?

6 0

3 years ago

Read 2 more answers

A proton moves through a region containing a uniform electric field given by E = 56.0 j V/m and a uniform magnetic field B = (0.

mina [271]

Answer:

$a = \dfrac{(9.57\times 10^{7})(57 \hat{k} - 20\hat{j})}$

Explanation:

given,

E = 56.0 j V/m

B = (0.2 i + 0.3 j + 0.4 k ) T

v = 190 i m/s

mass of proton = 1.67 x 10⁻²⁷ Kg

e = 1.6 x 10⁻¹⁹ C

acceleration of proton is equal to = ?

magnetic force

F_B = e v B

F_B = e x (190 i) x (0.2 i + 0.3 j + 0.4 k)

F_B = e x (57 k - 76 j)

for proton electric force

$F_e = 56 \times e \hat{j}$

$F_{net} = F_A + F_B$

$F_{net} = e(57 \hat{k} - (76-56) \hat{j})$

$F_{net} = e(57 \hat{k} - 20\hat{j})$

$a = \dfrac{1.6\times 10^{-19}}{1.67\times 10^{-27}}(57 \hat{k} - 20\hat{j})$

$a = (9.57\times 10^{7})(57 \hat{k} - 20\hat{j})$

6 0

2 years ago

If the coefficient of static friction between a table and a uniform massive rope is μs, what fraction of the rope can hang over

astra-53 [7]

Let me give you the procedure like this:
Lets say that F is the fraction of the rope hanging over the table
If its like that then we have to take into account that the friction force keeping on table is given by the following formula:
Ff = u*(1-f)*m*g 
and we need to know aso that gravity force pulling off the table Fg is given by this other formula:
Fg = f*m*g 
What you need to do is Equate the two and solve for f: 

f*m*g = u*(1-f)*m*g 
=> f = u*(1-f) = u - uf 
=> f + uf = u 
=> f = u/(1+u) = fraction of rope
With that you can find the answer

8 0

2 years ago

Read 2 more answers

A cube of water 10 cm on a side is placed in a microwave beam having Ea = 11 kV/m‘ The microwaves illuminate one faceofthe cube,

Shtirlitz [24]

Answer:

The time is 133.5 sec.

Explanation:

Given that,

One side of cube = 10 cm

Intensity of electric field = 11 kV/m

Suppose How long will it take to raise the water temperature by 41°C Assume that the water has no heat loss during this time.