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Keith_Richards [23]
3 years ago
13

A train travels 99 kilometers in 2 hours, and then 90 kilometers in 3 hours. What is its average speed?

Physics
1 answer:
Agata [3.3K]3 years ago
3 0

Average speed =

(total distance)/(total time)

Average speed = (99+90)/(2+3)

That's (189 km) / (5 hr)

Average speed = 37.8 km/hr

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A magnesium oxide component must not fail when a tensile stress of 10.5 MPa is applied. Determine the maximum allowable surface
Aloiza [94]

Answer:

Maximum permitted surface crack length is 1.29 mm

Explanation:

As per the question:

Tensile stress, \sigma = 10.5\ MPa = 10.5\times 10^{6}\ Pa

Surface energy of magnesium oxide, SE = 1.0\ J/m^{2}

Modulus of elasticity of the material, E = 225 GPa = 225\times 10^{9}\ Pa

Now,

To calculate the maximum allowable surface crack length:

L = \frac{2E\times SE}{\sigma^{2}\pi }

L = \frac{2\times 225\times 10^{9}\times 1.0}{10.5\times 10^{6}\times \pi } = 1.29\times 10^{- 3}\ m = 1.29\ mm

7 0
3 years ago
Describe how the composition of gases changes as you travel up through Earth's atmosphere.
Ghella [55]
<span>As the gases go higher in the atmosphere they start to compose or join together</span>
7 0
3 years ago
Which equation is used to calculate the electric potential in an electric field from a point charge?
scZoUnD [109]

Answer:

The electric potential (voltage) V produced by a point charge Q, at any point in space, is given by the following equation:

V=k\frac{Q}{r}

Where:

k=8.99(10)^{9} Nm^{2}/C^{2} is the Coulomb's constant

r is the distance  

The result is a scalar quantity, is defined as the electric potential energy per unit of charge and determines the electric influence exerted by the charge on that point of space.

6 0
3 years ago
A paint can is sitting on a ladder 20 m high. It has a mass of 7 kg. What is the
loris [4]

Answer:

<h3>The answer is 1400 J</h3>

Explanation:

The potential energy of a body can be found by using the formula

PE = mgh

where

m is the mass

h is the height

g is the acceleration due to gravity which is 10 m/s²

From the question we have

PE = 20 × 10 × 7

We have the final answer as

<h3>1400 J</h3>

Hope this helps you

3 0
3 years ago
What is the chemical formula for Tetrasulfur pentoxide <br>( explain)<br>​
juin [17]

Answer:

s4n4 the chemical formula

6 0
3 years ago
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