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Pavlova-9 [17]
3 years ago
8

A sample of hydrated calcium sulfate has a mass of 20.88 g. After it is heated, it has a mass of 16.51 g. What is the percentage

by mass of water in the hydrate? Use the formula mc010-1.jpg 4.37% 20.9% 26.5% 43.7%
Physics
2 answers:
STALIN [3.7K]3 years ago
6 0
We know that when you heat up calcium sulfate all the water has evaporated from it. That means that the mass of water that was initially in the sulfate is the difference in mass of the sulfate before and after the heating.
m{_H__20}=20.88-16.51=4.37g
In order to <span>get a percentage by mass we simply divide this number by the initial amount of sulfate:
</span>\%_{H__2}O=\frac{4.37}{20.88}=20.93\%<span>
</span>
nexus9112 [7]3 years ago
6 0
The answer is B) 20.9%
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An elevator car has a mass of 750 kg, and its three passengers have a combined mass of 135 kg. If the elevator and its passenger
joja [24]

Answer:

The change in gravitational potential energy is -1.80x10⁵ J.

Explanation:

The change in gravitational potential energy is given by:

\Delta E_{p} = E_{p_{f}} - E_{p_{i}}

\Delta E_{p} = mgh_{f} - mgh_{i}

Where:

"i" is for final and "f" for final

m: is the mass

g: is the gravity = 9.81 m/s²

h: is the height

For the car and the passengers we have:

\Delta E_{p} = m_{T}g(h_{f} - h_{i}) = (750 kg + 135 kg)9.81 m/s^{2}(0 - 20.7 m) = -1.80 \cdot 10^{5} J      

The minus sign is because when the elevator car and the passengers are up they have a bigger gravitational potential energy than when they are in the ground.

Therefore, the change in gravitational potential energy is -1.80x10⁵ J.

I hope it helps you!                                                

3 0
3 years ago
The temperature at a point (x, y) on a flat metal plate is given by T(x, y) = 54/(7 + x2 + y2), where T is measured in °C and x,
ANTONII [103]

Answer:

dt/dx = -0.373702

dt/dy =  -1.121107

Explanation:

Given data

T(x, y) = 54/(7 + x² + y²)

to find out

rate of change of temperature with respect to distance

solution

we know function

T(x, y) = 54 /( 7 + x² + y²)

so derivative it x and y direction i.e

dt/dx = -54× 2x / (7 +x² + y²)²    .........................1

dt/dy = -54× 2y / (7 + x² + y²)²      .........................2

now put the value point (1,3) as x = 1 and y = 3 in equation 1 and 2

dt/dx = -54× 2(1) / (7 +(1)² + (3)²)²  

dt/dx = -0.373702

and

dt/dy =  -54× 2(3) / (7 + (1)² + (3)²)²

dt/dy =  -1.121107

7 0
3 years ago
An example of a high energy electromagnetic wave is
Wewaii [24]
<span>An example of a high energy electromagnetic wave is "X-Ray"

When car runs, it's chemical energy (gasoline) converts into mechanical energy

Temperature is the measure of hotness or coldness of the body, so when heat expose to a substance, it's degree of hotness increases & it's temperature increases

Hope this helps!
</span>
4 0
3 years ago
Hello!
34kurt
Iodine-131 has a half life of 8 days, so half of it is gone every 8 days.
10 grams of iodine-131 is left for 24 days.
At 8 days: 10/2=5 grams left
At 16 days: 5/2=2.5 grams left
At 24 days: 2.5/2=1.25 grams left.
**
Your mistake is that you stopped at 16 days.
8 0
3 years ago
Using the picture above, which ball has the greatest potential energy?
weqwewe [10]
Ball 4 because the higher the elevation is the greater the potential energy it has
4 0
3 years ago
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