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vladimir1956 [14]
3 years ago
15

You drive your car for 2.0 h at 40.0 km/h then for 2.0 h at 60.0 km/h what is your average velocity?

Physics
1 answer:
Verdich [7]3 years ago
7 0
In order to calculate velocity, we'd need to know the straight-line distance between the start and the finish, and we'd also need the direction of that line.  The best we can do with the information given in the question is calculate the average SPEED.

Average speed = (total distance covered) / (time to cover the distance).

Distance covered in the first 2 hours = (2 hr) x (40 km/hr) = 80 km.
Distance covered in the second 2 hours = (2 hr) x (60 km/hr) = 120 km.

Total distance covered = (80 + 120) = 200 km
Time to cover the distance = (2 + 2) = 4 hours

Average speed = (200 km) / (4 hours)  =  50 km/hour
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the skill level of players

Explanation:

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What happens to the average kinetic energy of water molecules as water freezes
Mekhanik [1.2K]

Answer:

C. It decreases as the water releases energy to its surroundings

Explanation:

The energy that is possessed in the body because of the motion is said to be kinetic energy. When the water freezes, the kinetic energy of the water molecules decreases as the particles stop motion. The energy is released in the surrounding. Freezing takes place when the liquid molecules slow down and lose the kinetic energy to form the solid crystals.

6 0
3 years ago
In the first stage of a two-stage Carnot engine, energy is absorbed as heat Q1 at temperature T1 = 500 K, work W1 is done, and e
Nataly [62]

Answer:

Efficiency = 52%

Explanation:

Given:

First stage

heat absorbed, Q₁ at temperature T₁ = 500 K

Heat released, Q₂ at temperature T₂ = 430 K

and the work done is W₁

Second stage

Heat released, Q₂ at temperature T₂ = 430 K

Heat released, Q₃ at temperature T₃ = 240 K

and the work done is W₂

Total work done, W = W₁ + W₂

Now,

The efficiency is given as:

\eta=\frac{\textup{Total\ work\ done}}{\textup{Energy\ provided}}

or

Work done = change in heat

thus,

W₁ = Q₁ - Q₂

W₂ = Q₂ - Q₃

Thus,

\eta=\frac{(Q_1-Q_2)\ +\ (Q_2-Q_3)}{Q_1}}

or

\eta=1-\frac{(Q_1-Q_3)}{Q_1}}

or

\eta=1-\frac{(Q_3)}{Q_1}}

also,

\frac{Q_1}{T_1}=\frac{Q_2}{T_2}=\frac{Q_3}{T_3}

or

\frac{T_3}{T_1}=\frac{Q_3}{Q_1}

thus,

\eta=1-\frac{(T_3)}{T_1}}

thus,

\eta=1-\frac{(240\ K)}{500\ K}}

or

\eta=0.52

or

Efficiency = 52%

8 0
4 years ago
Choose all the answers that apply.
slava [35]
<h2>So, the correct answers are:</h2>

Travels in longitudinal waves

Travels most slowly through a gas

Speeds up when temperature is increased

Is caused by vibration

Explanation for correct answers:

Yes, it does travel in longitudinal waves

Yes, sounds weird, but travels faster in the water

Yes, does speed up when temperature is increased

And yes, Is caused by vibration.

<h2>Wrong answer is:</h2>

Can travel through a vacuum

Explanation for wrong answer:

actually, in space, there is NO sound, because there are no particals for the sound to vibrate with, there's just empty SPACE.

5 0
2 years ago
a man can swim in still water with speed of 2kmhr-1 wants to cross a river 200m wide flowing with 1kmhr-1 . Calculate the time t
tangare [24]

Answer:

d savage

Explanation:

3 0
3 years ago
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