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wolverine [178]
3 years ago
9

You are walking toward the back of a train that is moving forward with a constant velocity. The train's velocity relative to the

ground is 30 m/s forward. Your velocity relative to the train is 1.5 m/s backward. How fast are you moving relative to the ground?
Physics
1 answer:
yawa3891 [41]3 years ago
7 0

Answer:

28.5 m/s

Explanation:

There are 2 different velocities: the train velocity and yours velocity. They're in opposite directions, so one is positive and other is negative. Take the forward direction as the positive:

V = +30 -1.5

V = 28.5 m/s

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Which is not a common property of ionic compounds?
Dmitriy789 [7]

Answer:

low melting point

Ionic compounds have high melting and boiling points. This is because a considerable amount of energy is required to break the strong inter-ionic attraction

Explanation:

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3 years ago
A 10kg oil is heated by a source of heat that supplies 800J of heat every minute. Calculate The heat added to oil after 30 minut
goblinko [34]

Answer:

4,200 joules per kilogram per degree Celsius

Explanation:

The specific heat capacity of a material is the energy required to raise one kilogram (kg) of the material by one degree Celsius (°C). The specific heat capacity of water is 4,200 joules per kilogram per degree Celsius (J/kg°C). This means that it takes 4,200 J to raise the temperature of 1 kg of water by 1°C.

4 0
2 years ago
sedimentary rocks are formed due to the …..1-cooling of magna2 weathering of rocks 3 changes in pressure4 changes in temperature
Korolek [52]

Answer:

2

Explanation:

Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. This sediment is often formed when weathering and erosion break down a rock into loose material in a source area.

4 0
3 years ago
A man standing on the Earth can exert the same force with his legs as when he is standing
statuscvo [17]

Answer:

No

Explanation:

From the analogy of the problem we are made to know that "a man standing on the earth can exert the same force with his legs as when he is standing on the moon".

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      weight  = mass x acceleration due gravity

His mass and acceleration due to gravity on both terrestrial bodies are the same.

So, his jump height will be the same on earth and on the moon.

In summary, we have been shown that his mass and the acceleration due to gravity on both planets are the same, therefore, his weight will also be the same. His jump height will also be same.

7 0
2 years ago
A ship's anchor weighs 5000N. It's cable passes over a roller of negligible mass and is wound around a hollow cylindrical drum o
deff fn [24]
Hi! Great first step would be to understand the scenario (in my opinion). So two great ways would be to draw a picture or rephrase it. If something else works, do that! You just need to "see" the situation so that you can take some away from it.

Then I think a good next step is to conceptualize everything. Put everything into a context like a physics book would. The anchor is pulled 5000N downward - that's weight. The roller will act like a pulley, and we can ignore it's properties except that it's part of a pulley system (we can ignore stuff because it has "negligible" mass and no other details are given). And then we have the hollow cylindrical drum with one radius measurement given; so we can think of this as a made-up shape with mass - a cylindrical soda can without a top or bottom (but no thickness) and a 380kg mass. The anchor is drops 16m. It hints at energy. The energy that the drum gets is all do to this anchor pulling on the rope (which is really just a means of transferring force, since we neglect its mass and get no details).

Feel free to pause here to make sure you can get the scenario in your head.

So, we want to know something about the barrel as it's rolling. The rotation rate. How many turns per some time. But don't worry yet, we can find a way to work that in. Since the rope pulls and spins the drum, the drum is spun, and gets energy. One way to find the kinetic energy of the spinning drum uses the radius, mass, and rate of rotation. More on that soon.

And how does having some equation with the drum's kinetic energy, radius, mass, and rate of rotation help? Well, we can find all of those except our rate of rotation and solve for the rate of rotation. The energy is the only mystery, but that all comes from the dropping anchor. Can we find that energy? Yeah, there's a way to find the energy that gravity gives our anchor based on it's the force and how far that force moves it.

So, first for the anchor. Linear work is simple:  W=F d
So you have your force and distance we associate with the anchor, so you have your work. We'll call that "W_1" when we need it.

Next the drum's situation. Thanks to http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html, we have the equation for kinetic energy.
Generally, we have <em></em>KE=\frac12I\omega^2, and we need the "I," which deals with rotational inertia. That is pretty much how hard it is to rotate the drum based only on the idea that your getting the mass to move (acceleration). That site refers to our hollow drum as a "hoop," and gives says that we can consider the rotational inertia to be I=MR^2. Now that we know the rotational inertia, we can use good old mathematical substitution to get the kinetic energy to look like
KE=\frac12MR^2\omega^2
And we can rearrange that to get
\omega=\sqrt{\frac{2KE}{MR^2}}=\sqrt{\frac{2KE}{M}}\cdot\frac1R

Since the energy change from the anchor's fall is the energy change of the drum, this KE is the "W_1" from before. So
\omega=\sqrt{\frac{2W_1}{M}}\cdot\frac1R=\sqrt{\frac{2\left(F d\right)}{M}}\cdot\frac1R

Now everything's set up. It's a matter of checking my work, carefully using a calculator, and making sure the answer makes sense (ie. this should be a lot of energy - much more than 1 Joule). Also, follow up by making sure you can do it again, alone. And feel free to ask or lookup questions you need along the way if there are missing pieces in your understanding.

Good luck! :)
5 0
3 years ago
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