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slega [8]
3 years ago
5

2. How can people know that they've learned?

Physics
1 answer:
photoshop1234 [79]3 years ago
4 0
Answer: People know that they jap e learned by their mistakes or by someone ya being them something
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The reaction of H2 with F2 produces HF with ΔH = –269 kJ/mol of HF. If the H–H and H–F bond energies are 432 and 565 kJ/mol, res
ryzh [129]

Answer:

The bond energy of F–F = 429 kJ/mol

Explanation:

Given:

The bond energy of H–H = 432 kJ/mol

The bond energy of H–F = 565 kJ/mol

The bond energy of F–F = ?

Given that the standard enthalpy of the reaction:

<u>H₂ (g) + F₂ (g) ⇒ 2HF (g)</u>

ΔH = –269 kJ/mol

So,

<u>ΔH = Bond energy of reactants - Bond energy of products.</u>

<u>–269 kJ/mol = [1. (H–H) + 1. (F–F)]  - [2. (H–F)]</u>

Applying the values as:

–269 kJ/mol = [1. (432 kJ/mol) + 1. (F–F)]  - [2. (565 kJ/mol)]

Solving for , The bond energy of F–F , we get:

<u>The bond energy of F–F = 429 kJ/mol</u>

5 0
4 years ago
A projectile, fired with unknown initial velocity, lands 20sec later on side of hill, 3000m away horizontally and 450m verticall
lorasvet [3.4K]

Explanation:

Given:

t = 20 seconds

x = 3000 m

y = 450 m

a) To find the vertical component of the initial velocity v_{0y}, we can use the equation

y = v_{0y}t - \frac{1}{2}gt^2

Solving for v_{0y},

v_{0y} = \dfrac{y + \frac{1}{2}gt^2}{t}

\:\:\:\:\:\:\:=\dfrac{(450\:\text{m}) + \frac{1}{2}(9.8\:\text{m/s}^2)(20\:\text{s})^2}{(20\:\text{s})}

\:\:\:\:\:\:\:=120.5\:\text{m/s}

b) We can solve for the horizontal component of the velocity v_{0x} as

x = v_{0x}t \Rightarrow v_{0x} = \dfrac{x}{t} = \dfrac{3000\:\text{m}}{20\:\text{s}}

or

v_{0x} = 150\:\text{m/s}

4 0
3 years ago
True or false. Magnetic force fields are straight lines.<br> O False<br> O True
swat32

Answer:

oop false have a great day

Explanation:

i hope i helped u

8 0
3 years ago
Read 2 more answers
What does a battery powered heater warms up from ?
Westkost [7]
Battery based heaters use electric resistance heating, which uses a lot of current (electricity) to create the heat.
8 0
3 years ago
A professor's office door is 0.91 m wide, 2.0 m high, and 4.0 cm thick; has a mass of 25 kg; and pivots on frictionless hinges.
olasank [31]

Answer:

F= 5.71 N

Explanation:

width of door= 0.91 m

door closer torque on door= 5.2 Nm

In order to hold the door in open position we need to exert an equal and opposite torque, to the door closer torque, on the door.

so wee need to exert 5.2 Nm torque on the door.

If we want to apply minimum force to exert the required torque we need to apply force perpendicularly on the door knob (end of door) so that to to greater moment arm.

T= r x F

T= r F sin∅

F= T/ (r * sin∅)

F= 5.2/ (0.91 * 1)

F= 5.71 N

5 0
4 years ago
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