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# Questions posted in Physics

### Earth's oceans have an average depth of 3800 m, a total area of 3.63 × 108 km2, and an average concentration of dissolved gold of 5.8 × 10?9 g/l. how many grams of gold are in the oceans? enter your answer in scientific notation.

To determine the mass of gold dissolved in oceans, we must first know the volume of the ocean in liters. To determine its volume, we multiply the area and the depth taking note of the consistency of units. The volume would be 1.38 x 10^18 cubic meters or 1.38x10^21 liters. Then,multiplying this to the concentration, the answer would be 8 x 10^12 grams or 8 billion kg.

ANSWERED AT 02/06/2020 - 01:44 AM

QUESTION POSTED AT 02/06/2020 - 01:44 AM

### When cooking food in a microwave, why is it more important to rely on the internal temperature of the food rather than on a previous cooking time?

When cooking food in a microwave it is more important to rely on the internal temperature of the food because microwave do not adequately kills pathogens that may be in food.  Microwave normally penetrate food to the depth of 1 to 1.5 only. In thicker foods, microwave doesn't usually reach the center of the food, the un-reached part normally cook by conduction.

ANSWERED AT 02/06/2020 - 01:43 AM

QUESTION POSTED AT 02/06/2020 - 01:43 AM

### A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. during this interval its acceleration is

The acceleration is 1

ANSWERED AT 02/06/2020 - 01:42 AM

QUESTION POSTED AT 02/06/2020 - 01:42 AM

### A piece of purple plastic is charged with 8.51 × 106 extra electrons compared to its neutral state. what is its net electric charge (including its sign) in coulombs.

Each electron provides a charge of -1.602 × 10^-19 coulombs.

If there are 8.51 × 10^-6 extra electrons:

1 electron ­____________ -1.602 × 10^-19 coulombs

8.51 × 10^6 electrons___x = -1.602 × 10^-19*8.51 × 10^6/1=-1.32× 10^-12 coulombs

So the extra electrons provide a charge of 1.32× 10^-12 coulombs.

So the net charge is -1.32× 10^-12 coulombs (there are more electrons besides those extra electrons, but there are also protons, so they don’t affect the net charge – the other electrons just compensate the charge of the protons).

ANSWERED AT 02/06/2020 - 01:41 AM

QUESTION POSTED AT 02/06/2020 - 01:41 AM

### Arrange the stars based on their temperature. Begin with the coolest star, and end with the hottest star. Tiles yellow red blue white Sequence

Red,yellow,white,and blue
Hope this helps!

ANSWERED AT 02/06/2020 - 01:37 AM

QUESTION POSTED AT 02/06/2020 - 01:37 AM

### A parachutist of mass 75kg descends with an acceleration of 8 m/s2. What is the upward force exerted by the air on the parachutist?

The upwards force should be 150 newtons.
If    mg - f = ma
then   (75)(10) - f = (75)(8)
750 - f = 600
f = 150
*the acceleration of gravity is simplified to 10

ANSWERED AT 02/06/2020 - 01:37 AM

QUESTION POSTED AT 02/06/2020 - 01:37 AM

### An unmanned spacecraft travels to Mars. Mars has a lower strength of gravity than Earth. Where is the spacecraft’s weight the greatest?

Mars has a lower strength of gravity than Earth - 62% lower .
The connection between the weight and the force is the following: Weight is the force caused by gravity. The weight of an object is the gravitational force between the object and the Earth. So,
a person who weighs 100 kg on Earth would weigh only 38 kg on Mars.
According to this, the unnamed spacecraft which travels to Mars, will have the greatest weight on the Earth.

ANSWERED AT 02/06/2020 - 01:35 AM

QUESTION POSTED AT 02/06/2020 - 01:35 AM

### In nature, where do fusion reactions take place?

Fusion reactions happen in stars

ANSWERED AT 02/06/2020 - 01:34 AM

QUESTION POSTED AT 02/06/2020 - 01:34 AM

### 1. An object is moving to the right in a straight line. The net force acting on the object is also directed to the right, but the magnitude of the force is decreasing with time. How will the motion of the object change? a. It will continue to move to the right, its speed increasing with time. b. It will stop and then begin moving to the left. c. It will continue to move to the right at a constant speed. d. It will continue to move to the right, its speed decreasing with time. 2. A glass table top is able to exert a maximum normal force of 1600 N. A large object with a mass of 165 kg is gently lowered onto the center of the table top, then released there. What most likely will happen next? a. The table top will crack but still hold the object. b. The table top will break and the object will fall to the floor. c. The object will bounce off the table. d. The object will rest on the table top, which remains in tact. 3. A rock at rest has weight 138 N. What is the weight of the rock when it is accelerating upward at 12 m/s2? a. 115 N b. 63 N c. 304 N d. 138 N 4. A chair of mass 30.0 kg is at rest on a horizontal floor. The floor is not frictionless. You push on the chair with a force of 80.0 N directed at an angle of 35.0° to the floor. What is the normal force that the floor exerts on the chair? a. 363 N b. 340 N c. 294 N d. 317 N 5. Two particles are separated by a distance d. At this distance, the strong interaction between them is much greater than the electrical interaction. What are the possible values of d? a. extremely large values, such as the distances between the planets and sun b. extremely small values, such as the distances between particles in an atomic nucleus c. values between 1 mm and 1 m d. values between 1 m and 1 km 6. A soccer player kicks a ball. Why does the action force exerted by the player's foot cause a different motion than the reaction force? a. The action force and the reaction force act on different objects. b. The action force is greater than the reaction force. c. The reaction force is greater than the action force. d. The action force and the reaction force act in opposite directions. 7. A box of weight 320 N is being pulled to the right by a pulling force F-> of magnitude 44 N. The coefficient of static friction between the box and the floor is 0.15. To make an accurate free-body diagram of the box, the letter f in the diagram above should be replaced with the label _____. a. 4.0 N b. 48 N c. 44 N d. 280 N 8. I have the answer 9. A man pulls a wagon with a handle that is at an angle of 42° with the ground. If the man pulls with 330 N of force, how much force pulls the wagon forward? a. 110 N b. 220 N c. 245 N d. 330 N 10. In this free-body diagram, the weight (W) and normal force (n) have equal magnitudes. The magnitudes of any forward or backward forces, however, are not determined. The free-body diagram will not apply to which of these objects or persons? a. a box sliding across a table at constant speed b. an automobile accelerating on a flat highway c. a box at rest on a table d. a woman jumping off the floor 11. A force of 1 N will cause a mass of 1 kg to have an acceleration of 1 m/s2. Therefore, a force of 8 N applied to a mass of 1 kg will cause it to accelerate at what rate? a. 8 m/s2 b. 0.13 m/s2 c. 1 m/s2 d. 9 m/s2 e. 64 m/s2

1. I am definitely sure that correct option is: a. It will continue to move to the right, its speed increasing with time. If the object is experiencing a net force to the right, it always accelerates to the right => the velocity is increasing, because the greater the force, the larger the acceleration.

2. In my opinion the answer should be
b. The table top will break and the object will fall to the floor. We should count the normal force of the object. According to the conditions, we can use N=mg; N=165*9,8 = 1617 N. 1617 > 1600. That's why I've picked this option.

3. It's tricky question, because the weight of the rock depends only on the force of gravity. Speed doesn't affect the weight of the object. So it doesn't matter what the acceleration is, its force will be 138 N. So the answer is D.

4. The friction doesn't matter. We should use Newton's laws to define
the normal force that the floor exerts on the chair.
So the solution is: ; where  ;
so the most approximate answer is B. 340 N.

5. I am pretty sure that correct answer is: b. extremely small values, such as the distances between particles in an atomic nucleus. According to its definition, strong interaction is a mechanism that is responsible responsible for the acts between subatomic particles of matter.

6. As far as I remember the correct option is:
a. The action force and the reaction force act on different objects. Action and reaction forces are very important forces of a single interaction and they are not exist without each other. They're both equal in strength but opposite in direction.

7. I am not completely sure, but I think that the answer should be 48 N. We have normal force which is equal to the box's weight, so n = 320 N. Then we can count force of friction using the formula f = n*
μ where μ = 0.15.  8. -

9. We have and . And this is all we need to find the real force that pulls the wagon forward.
The formula is: ; ;

So the most approximate answer is C. 245 N.

10. According to the free-body diagram given above, the answer should be d. a woman jumping off the floor. Because in this option the object is experiencing a vertical acceleration, and this means that the normal force acting on the object will not be equal to the weight of the object.

11. According to the Newton's second law of motion  So the answer is  A. 8 m/s^2

ANSWERED AT 02/06/2020 - 01:27 AM

QUESTION POSTED AT 02/06/2020 - 01:27 AM

### You toss a coin into a eishimg well full of a liquid denser than the coin which of the following could be true the coin will

Then the coin will float on the surface of the liquid in the eishimg well.

ANSWERED AT 02/06/2020 - 01:25 AM

QUESTION POSTED AT 02/06/2020 - 01:25 AM

### If a pulley system with an actual mechanical advantage of 2,000,000 is used in lifting a 2,000 lb. car, what effort would be needed to move the car?

Well I must say that's a very interesting machine you've got there. It wouldn't be possible to build a system with an actual mechanical advantage of 2 million. But if you did have such a thing, and you wanted to use it to lift a 2000 pound weight, then you would only need to pull with a force of 1.6% of an ounce ! The bad news is that in order to lift the weight one foot, you'd have to pull about 379 miles of rope through the pulley system !

ANSWERED AT 02/06/2020 - 01:23 AM

QUESTION POSTED AT 02/06/2020 - 01:23 AM

### What kind of electronic component is an LED (light emitting diode)?

A light emitting diode (LED) is one example of the electronic components called "diodes". It has an interesting characteristic that makes it very useful. When current is flowing through it in the forward (easy) direction, light comes out of it.

ANSWERED AT 02/06/2020 - 01:22 AM

QUESTION POSTED AT 02/06/2020 - 01:22 AM

### A man stands still on a moving escalator and a woman walks past him in the same direction as the escalator. to a stationary observer the man has a speed of 0.2 m/s and the woman has a speed of 0.5 m/s from the frame or reference of the man on the escalator how fast is the woman walking?

Let Ve =  speed of escalator
Let  Vm = speed of the man (Vm=0 because he is stationary)
Let Vw =  speed of woman

According to the stationary observer,
Because the man stands still on the escalator, his speed is Ve = 0.2 m/s.
The speed of the woman is Ve + Vw = 0.5 m/s

Therefore
0.2 + Vw = 0.5
Vw = 0.3 m/

The woman is walking at 0.3 m/s.

ANSWERED AT 02/06/2020 - 01:21 AM

QUESTION POSTED AT 02/06/2020 - 01:21 AM

### You hired a contract to update electrical wiring in your house.After the work, the outlets in your kitchen all shorted out. The contractor refused to return to do the work without additional payment. which kind of state court would you take the contract to?

Federal court
(not 100% sure)

ANSWERED AT 02/06/2020 - 01:21 AM

QUESTION POSTED AT 02/06/2020 - 01:21 AM

### A student was taking a rock-climbing class that used an indoor climbing wall. Before he started, the instructor asked for his weight. If the student had a mass of 88.6 kg, what was his weight?

F = m*g
F = 88.6 * 10 = 886 N

ANSWERED AT 02/06/2020 - 01:19 AM

QUESTION POSTED AT 02/06/2020 - 01:19 AM

### Discuss the relationship between amperage, voltage, and power.

In an electric circuit, power is the product of amperage (current) times voltage.

ANSWERED AT 01/06/2020 - 05:09 PM

QUESTION POSTED AT 01/06/2020 - 05:09 PM

### Which statement describes the horizontal acceleration of a projectile? It is –9.8 m/s2. It is 9.8 m/s2. It is constant. It is zero.

In a projectile, the horizontal acceleration is zero. The velocity remains constant at all times. However, the vertical acceleration is -9.81m/s^2.

Hope this helps!

ANSWERED AT 01/06/2020 - 04:49 PM

QUESTION POSTED AT 01/06/2020 - 04:49 PM

### Two scientists have a difference of opinion about something supernatural and they engage in a rational argument.What can we call this

That would be a philosophy

ANSWERED AT 01/06/2020 - 04:47 PM

QUESTION POSTED AT 01/06/2020 - 04:47 PM

### A scientific question should be vague creative non-testable non-repeating

The question should be D: Non-repeating

ANSWERED AT 01/06/2020 - 04:46 PM

QUESTION POSTED AT 01/06/2020 - 04:46 PM

### Juan makes an adjustment to an electromagnet that causes the electromagnet to lose some of its strength. What did Juan most likely do?

Reducing the amount of loops will cause a loss of strength, as the loops make the magnet stronger.

ANSWERED AT 01/06/2020 - 04:46 PM

QUESTION POSTED AT 01/06/2020 - 04:46 PM

### A puppy weighing 3 kilograms races through the dog park. If she slows from a speed of 2 meters/second to 1 meter/second, what will happen to her kinetic energy?

Ans: Thus, the kinetic energy change = 4.5 J

The mass of puppy = 3kg

Kinetic energy initial = = Kinetic energy final = Thus, the kinetic energy change = 4.5 J

ANSWERED AT 01/06/2020 - 04:43 PM

QUESTION POSTED AT 01/06/2020 - 04:43 PM

### Which is a good example of a contact force? A) Protons in the nucleus of an atom B) A ball falling down after it's thrown up into the air C) A satellite orbiting earth D) A bat hitting a ball

A ball hitting a ball so D

ANSWERED AT 01/06/2020 - 04:43 PM

QUESTION POSTED AT 01/06/2020 - 04:43 PM

### How do I calculate power?

Power=Work     Force * Displacement
-------- * -----------------------------
Time                Time

ANSWERED AT 01/06/2020 - 04:42 PM

QUESTION POSTED AT 01/06/2020 - 04:42 PM

### SCIENE HELP PLEASE Look at the picture below

The answer is D. hope it helps

ANSWERED AT 01/06/2020 - 04:40 PM

QUESTION POSTED AT 01/06/2020 - 04:40 PM

### A transformer primary has 100 V and 2 A. What is the voltage if the secondary has a current of 1 A? 100 V 25 V 400 V 50 V 200 V

50 V. I don't know if this is correct, mainly because I'm in 7th grade.

ANSWERED AT 01/06/2020 - 04:39 PM

QUESTION POSTED AT 01/06/2020 - 04:39 PM

### On my bike I was able to travel 40 miles in one hour from this information we can determine the bikes

You have a distance and a time so you can work out the bikes speed which would be distance/time so 40mph.

ANSWERED AT 01/06/2020 - 04:38 PM

QUESTION POSTED AT 01/06/2020 - 04:38 PM

### Tubes have a sides of equal lengths what is the fastest way to measure the volume of a cube shaped table

Work out one side then cube it to work out the volume. E.g if one side of the table was 2m then the volume would be 2x2x2 which is 8m cubed.

ANSWERED AT 01/06/2020 - 04:33 PM

QUESTION POSTED AT 01/06/2020 - 04:33 PM

### The energy that powers a hurricane is derived from?a.)a stationary front.c.)funnel clouds.b.)condensation of water vapor.d.)sublimation of water.

B. Condensation of water vapor

ANSWERED AT 01/06/2020 - 04:32 PM

QUESTION POSTED AT 01/06/2020 - 04:32 PM

### The metric system and metric conversions are?

The Metric System and Metric Conversions are both two different things , but still corresponds in a way. For example, the metric system is meter, liter, and gram as units of length. Metric conversions are when you use either meter, liter, or and gram and make a number to equal by moving a decimal.

ANSWERED AT 01/06/2020 - 04:28 PM

QUESTION POSTED AT 01/06/2020 - 04:28 PM

### You kick a soccer ball straight up into the air with a speed of 21.2 m/s how long does it take the soccer ball to reach its highest point

Calculate how high the highest point is then divid that number by 21.2 and that's how long it takes

ANSWERED AT 01/06/2020 - 04:26 PM

QUESTION POSTED AT 01/06/2020 - 04:26 PM