Answer:
= 85.7 ° C
Explanation:
For this exercise we will use the calorimetry heat ratios, let's start with the heat lost by the evaporation of coffee, since it changes from liquid to vapor state
Q₁ = m L
Where m is the evaporated mass (m = 2.00 103-3kg) and L is 2.26 106 J / kg, where we use the latent heat of the water
Q₁ = 2.00 10⁻³ 2.26 10⁶
Q1 = 4.52 10³ J
Now the heat of coffee in the cup, which does not change state is
Q coffee = M 
( -
)
Since the only form of energy transfer is terminated, the heat transferred is equal to the evaporated heat
Qc = - Q₁
M ce ( -) = - Q₁
The coffee dough left in the cup after evaporation is
M = 250 -2 = 248 g = 0.248 kg
-Ti = -Q1 / M
= Ti - Q1 / M
Since coffee is essentially water, let's use the specific heat of water,
= 4186 J / kg ºC
Let's calculate
= 90.0 - 4.52 103 / (0.248 4.186 103)
= 90- 4.35
= 85.65 ° C
= 85.7 ° C
Answer:
h=15.27m
Explanation:
Since at maximum height the vertical velocity must be null it's better to use the formula:
We will use this formula for the vertical direction, choosing the upward direction as the positive one, so we have:
or
which for our values is:
Answer:
The leverage or mechanical advantage of pulleys is less obvious, but you can "gang" multiple pulleys together into two sets (blocks) and run the ropes back and forth between the two sets to increase the number of lengths of rope running between them. One end of the rope is connected (fixed) to one of the blocks, and you get to pull on the other end after it is passed back and forth between the blocks of pulleys. This is sometimes called a block and tackle arrangement. With a hook on each side of the block set, you can move a heavy load much like levers do, by multiplying the force. You have to pull more rope just like you have to move a lever more on one side of the fulcrum as compared to the other. When you get all the rope pulled out that you can, you can not move the load anymore because you have become "two-blocked" which means the two blocks are together. Credits to: Moin Khan
Answer:
the answer is that the dough has the same mass before and after it was flattened
Answer:
Explanation:
The formula to determine the size of a capillary tube is
h = 2•T•Cos θ / r•ρ•g
Where
h = height of liquid level
T = surface tension
r = radius of capillary tube
ρ = density of liquid
θ = angle of contact = 0°
g =acceleration due to gravity=9.81m/s²
The liquid is water then,
ρ = 1000 kg / m³
Given that,
T = 0.0735 N/m
h = 0.25mm = 0.25 × 10^-3m
Then,
r = 2•T•Cos θ / h•ρ•g
r = 2 × 0.0735 × Cos0 / 2.5 × 10^-3 × 1000 × 9.81
r = 5.99 × 10^-3m
Then, r ≈ 6mm
The radius of the capillary tube is 6mm
So, the minimum size is
Volume = πr²h
Volume = π × 6² × 0.25
V = 2.83 mm³
The minimum size of the capillary tube is 2.83mm³
