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Alona [7]
2 years ago
12

A train travels 90 kilometers in 4 hours, and then 82 kilometers in 1 hours. What is its average speed?

Physics
1 answer:
kvasek [131]2 years ago
5 0
Average speed = total distance / total time.

That's 172 km / 5 hr = 34.4 km//hr
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The concept of critical density is just like the idea of escape velocity for a projectile launched from the earth. An object lau
ikadub [295]

Answer:

v = √ 2 G M/ R_{e}

Explanation:

To find the escape velocity we can use the concept of mechanical energy, where the initial point is the surface of the earth and the end point is at the maximum distance from the projectile to the Earth.

Initial

        Em₀ = K + U₀

Final

        Em_{f} =  U_{f}

The kinetic energy is k = ½ m v²

The gravitational potential energy is U = - G m M / r

r is the distance measured from the center of the Earth

How energy is conserved

       Em₀ =  Em_{f}

       ½ mv² - GmM / R_{e} = -GmM / r

       v² = 2 G M (1 /  R_{e} – 1 / r)

       v = √ 2GM (1 / R_{e} – 1 / r)

The escape velocity is that necessary to take the rocket to an infinite distance (r = ∞), whereby 1 /∞ = 0

        v = √ 2GM /  R_{e}

5 0
2 years ago
How much power does it take to do 500 J of work in 10 seconds?
Dmitry_Shevchenko [17]
Power = work/time
  
          = 500/10
 
          = 50J/s or 50 watt 


7 0
3 years ago
he Hobbits are building a watchtower so they can prepare to battle in case trolls decide to attack them. One Hobbit will always
joja [24]

Answer:

5m/8

Explanation:

Function T gives the time the Hobbits have to prepare for the attack, T(k), in minutes, as a function of troll's distance, k, in meters.

Function V gives visibility from the watchtower, V(m), in meters, as a function of the height of the watchtower, m, in meters.

Therefore, T(V(m)) will give the time the Hobbits have to prepare for the troll attack as a function of the height, m, of the watchtower.

We can input m into function V to obtain the visibility from watchtower, V(m), in meters. Since visibility indicates the distance you can see, this also gives the distance of the trolls. This can then be input into function T to obtain the time that the Hobbits have to prepare for a troll attack.

Let's find T(V(m)) by substituting the formula for V(m) into function T as shown below.

T(V(M))=T(50m)

=50m/80

We can simplify this as follows:

=50m/80

=5m/8

4 0
2 years ago
Which math formula will find density?
Sedbober [7]
Mass/volume is the formulae
8 0
3 years ago
Read 2 more answers
The ________________ is the measure of how far the pendulum is offset (or pulled back) from a vertical position when it is relea
Dahasolnce [82]
B. Amplitude

It is the maximum distance from the equilibrium point of the pendulum.
6 0
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