Explanation:
The dimensions of a standard backpack is 30cm x 30cm x 40cm
The mass of an average student is 70 kg
We know that, the density of gold is 19.3 g/cm³.
Let m be the mass of the backpack. So,
An average student has a mass of 70 kg. If we compare the mass of student and mass of backpack, we find that the backpack is 10 times of the mass of the student.
Given:
The overall average speed = 25 cm/s.
The overall average speed increased by 10%.
To find:
The new overall average speed.
Solution:
We have,
Overall average speed = 25 cm/s.
The overall average speed increased by 10%. So, the new average speed is
New overall average speed = Initial average speed + 10% of initial overall average speed
Therefore, the new overall average speed is 27.5 cm/s.
Answer:
Mass of KCL = 218 grams.
Explanation:
Step 1: calculate the heat that must be absorbed(q).
Heat that must be absorbed(q) is calculated as follows:
q= m c (T2-T1).
q = 750g (4.18 J/gC)(20-4 C) = 5.016X10^4 J = 50.16 kJ
Step 2: we determine moles of KCL as follows:
Moles KCl = 50.16 kJ / 17.2 kJ/mol = 2.92 moles.
Step 3: calculate mass of KCL:
Mass of KCl = 2.92 mol X 74.55 g/mol = 218g.
Therefore, 218 grams of KCL would have to be dissolved into 750 g of 20.0°C H2O to produce the solution.
<span>6.50x10^3 calories.
Now we have 4 pieces of data and want a single result. The data is:
Mass: 100.0 g
Starting temperature: 25.0°C
Ending temperature: 31.5°C
Specific heat: 1.00 cal/(g*°C)
And we want a result with the unit "cal". Now you need to figure out what set of math operations will give you the desired result. Turns out this is quite simple. First, you need to remember that you can only add or subtract things that have the same units. You may multiply or divide data items with different units and the units can combine or cancel each other. So let's solve this:
Let's start with specific heat with the unit "cal/(g*°C)". The cal is what we want, but we'ld like to get rid of the "/(g*°C)" part. So let's multiply by the mass:
1.00 cal/(g*°C) * 100.0 g = 100.0 cal/°C
We now have a simpler unit of "cal/°C", so we're getting closer. Just need to cancel out the "/°C" part, which we can do with a multiplication. But we have 2 pieces of data using "°C". We can't multiply both of them, that would give us "cal*°C" which we don't want. But we need to use both pieces. And since we're interested in the temperature change, let's subtract them. So
31.5°C - 25.0°C = 6.5°C
So we have a 6.5°C change in temperature. Now let's multiply:
6.5°C * 100.0 cal/°C = 6500.0 cal
Since we only have 3 significant digits in our least precise piece of data, we need to round the result to 3 significant figures. 6500 only has 2 significant digits, and 6500. has 4. But we can use scientific notation to express the result as 6.50x10^3 which has the desired 3 digits of significance. So the result is 6.50x10^3 calories.
Just remember to pay attention to the units in the data you have. They will pretty much tell you exactly what to add, subtract, multiply, or divide.</span>
