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3 years ago

Which of the following is considered a physical change? burning paper rusting of metal evaporating water

1 answer:

6 0

When paper burns, some of the chemical compounds in the
paper combine with oxygen in the air and become different
chemical compounds. That's a chemical change.

When iron rusts, or copper or silver turns green, that's the result
of the metal at the surface combining with the oxygen in the air and
forming a new chemical compound. Those are chemical changes.

When water evaporates, H₂O in the liquid phase gains thermal
energy and changes to H₂O in the gaseous phase. No chemical
compounds are lost, gained, or changed to other compounds.
It's just a physical change.

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11. Which compound is the most soluble at 10°C?<br> a. Ce2(S04)3<br> b. NaCl<br> c. KCI<br> d. KCIO3

Rasek [7]

KCIO3 is the answer

6 0

3 years ago

A truck traveling at 80 mph runs into a bridge abutment and crumples for 0.8 m before coming to a full stop. If we estimate the

Anettt [7]

U = 80mph = 35.76m/s

S = 0.8m

M = 3500kg

To find the deceleration, we use equation of motion to calculate that

V² = u² + 2as

But v = 0

0 = u² + 2as

-U² = 2as

a = -u² / 2s

a = -(35.76)² / (2 * 0.8)

a = 1278.78 / 1.6 = 799.24 m/s²

The force exerted on the truck during deceleration is equal to the summation of all the forces acting on the truck.

∑F = m. ⃗a

-F = 3500 * 799.24

F = -2797331.25N

F = -2797.33kN

F = -2.797MN.

5 0

3 years ago

Which of the following statements is INCORRECT based on our Ray Model of Light?

viva [34]

Answer:

a and c

Explanation:

a)light moves in a straight line and distracts when it encounters an obstacle forming a shadow

c)the light rays from that object or also tgose from the image must enter your eye for you to see that image

8 0

3 years ago

A 1kg box is pushed on a flat surface that is 250m long. The box is initially at rest and then pushed with a constant Net force

sasho [114]

Answer:

C) 50 m/s

Explanation:

With the given information we can calculate the acceleration using the force and mass of the box.

Newton's 2nd Law: F = ma

5 N = 1 kg * a
a = 5 m/s²

List out known variables:

v₀ = 0 m/s
a = 5 m/s²
v = ?
Δx = 250 m

Looking at the constant acceleration kinematic equations, we see that this one contains all four variables:

v² = v₀² + 2aΔx

Substitute known values into the equation and solve for v.

v² = (0)² + 2(5)(250)
v² = 2500
v = 50 m/s

The final velocity of the box is C) 50 m/s.

7 0

3 years ago

In doing a load of clothes, a clothes drier uses 18 A of current at 240 V for 41 min. A personal computer, in contrast, uses 2.2

Tpy6a [65]

Answer:

The time taken by the personal computer to 'surf' the internet is 11.13 h.

Explanation:

The expression for the energy in terms of current and time is as follows;

E= Vit

Here, V is the potential, i is the current and t is the time.

According to question, in doing a load of clothes, a clothes drier uses 18 A of current at 240 V for 41 min.

Convert time from minute to second.

$t=\frac{41}{60}s$

Calculate the energy used by the clothes drier.

Put V= 240 V, $t=\frac{41}{60}s$ and i=18 A in the expression for the energy.

$E= (240)(18)\frac{41}{60}$

E'= 2937.6 W

Therefore, the energy of a clothes drier is E'= 2937.6 W.

It is given in the problem that a personal computer, in contrast, uses 2.2 A of current at 120 V. With the energy used by the clothes drier, this computer is used to surf the internet.

Calculate the time taken by the computer to 'surf' the internet.

E'=V'i't'

Here, V' is the voltage used by the a personal computer, i' is the current and t' is the time taken by the personal computer.

Put E'= 2937.6 W, V= 120 V and i'= 2.2 A.

2937.6 = (120)(2.2)t'

$t'=\frac{2937.6}{264}$

t'= 11.13 h

Therefore, the time taken by the personal computer to 'surf' the internet is 11.13 h.

4 0

4 years ago