PHYSICS COLLEGE

A group of hikers hears an echo 2.90 s after shouting. How far away is the mountain that reflected the sound wave? (Assume the speed of sound is 341 m/s.)

Answers

Answer 1
Answer:

Answer:

494.45 m.

Explanation:

Echo: This is the sound heard after the reflection of sound wave in a plain surface.

v = 2x/t................................ Equation 1

Where v = velocity of sound in air, x = distance between the mountain and the hikers, t = time to hear the echo.

making x the subject of the equation,

x = vt/2........................... Equation 2

Given: v = 341 m/s, t = 2.9 s.

Substitute into equation 2

x = 341(2.9)/2

x = 494.45 m.

Hence the mountain is 494.45 m far away


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HIGH SCHOOL

A bus travels 300 km south along a straight path with an average velocity of 85 km/h to the south. The bus stops for 22 minutes. Then it travels 220 km south with an average velocity of 78 km/h to the south. How long does the total trip last? What is the average velocity for the total trip?

Answers

a) Answer;

= 6.72 hours

Explanation and solution;

velocity = distance over time  

Since we know the velocity and the distance, we can simply calculate time  

For the first part  

85 km/h = 300km / time  

time = 3.53 hours  

Then there is a 22 min stop, which is the same as 0.37 hours  

so far the trip is:  

3.53 + 0.37 = 3.9 hours  

then for the last stretch:  

78 km/h = 220 km / time  

time = 2.82 hours  

So the total trip is:  

3.9 + 2.82  = 6.72 hours

b) Answer;  

=  77.38 km/hr

Explanation and solution;

we take the total distance divided by the total time to get the average.  

total distance = 300 km + 220 km = 520 km  

total time = 6.72 hours  

Average velocity = 520 km / 6.72 hours =  77.38 km/hr


HIGH SCHOOL

which is an example of action reaction forces?A)a deep space probe drifting in a straight path B)a tennis racket striking a tennis ball C)an air hockey puck moving at a constant speed

Answers

The answer is B.
____
a tennis racket striking a tennis ball
HIGH SCHOOL

Elaborate on the reason(s) that matter is said to move even as in a solid state. A) The particles are bound through intermolecular forces but are able to move past each other with relative freedom.
B) The particles have sufficient energy to become an ionized gas and are in the most common state of matter in the universe.
C) The particles are not able to move out of their positions relative to one another, but do have small vibrational movements.
D) The particles are not bound to one another, move quickly, have a low density, and are able to spread apart from one another if unconstrained.


Brad and Matt are working in the lab. They noticed that when they mixed two dilute solutions together, the reaction between them happened very slowly. Which of Matt's suggestions would BEST help to increase the rate of this reaction?

A) increase the concentration of both solutions
B) decrease the concentration of both solutions
C) increase the concentration of one of the solutions
D) decrease the concentration of one of the solutions


Identify the correct order of increasing intermolecular force of attraction for the three most common states of matter.
A) liquid → solid → gas
B) solid → liquid → gas
C) gas → liquid → solid
D) gas → solid → liquid

Answers

1) The correct answer is
C) The particles are not able to move out of their positions relative to one another, but do have small vibrational movements.
In solids, in fact, particles are bound together so they cannot move freely. However, they can move around their fixed position with small vibrational movements, whose intensity depends on the temperature of the substance (the higher the temperature, the more intense the vibrations). For this reason, we say that matter moves also in solid state.

2)  The correct answer is
A) increase the concentration of both solutions
In fact, when we increase the concentration of both solutions, we increase the number of particles that react in both solutions; as a result, the speed of the reaction will increase.

3)  The correct answer is
C) gas → liquid → solid
In gases, in fact, particles are basically free to move, so the intermolecular forces of attraction are almost negligible. In liquids, particles are still able to move, however the intermolecular forces of attraction are stronger than in gases. Finally, in solids, particles are bound together, so they are not free to move and the intermolecular forces of attraction are very strong. 
MIDDLE SCHOOL

On Earth, when a body is in motion, there is always __________ to oppose the motion. a. friction c. gravity b. inertia d. acceleration Please select the best answer from the choices provided

Answers

a. Friction

When a body is in motion given Newtons first law it will move in straight line with constant velocity unless acted on by a nonzero net force. Friction is most often this force.

Answer:

A. friction

Explanation:

COLLEGE

The bullet starts at rest in the gun. An 8.6 g bullet leaves the muzzle of a rifle with a speed of 430.1 m/s. What constant force is exerted on the bullet while it is traveling down the 0.5 m length of the barrel of the rifle?

Answers

Answer:

The constant force exerted on the bullet is 1590.87 N.

Explanation:

It is given that,

Mass of the bullet, m = 8.6 g

Initial speed of the bullet, u = 0          

Final speed of the bullet, v = 430.1 m/s

We need to find the force exerted on the bullet while it is traveling down the 0.5 m length of the barrel of the rifle. Let a is the acceleration of the bullet. So,

Let F is the force exerted. It is given by :

F = 1590.87 N

So, the constant force exerted on the bullet is 1590.87 N. Hence, this is the required solution.                                                  

MIDDLE SCHOOL

The older, geocentric model of the solar system placed the__________ at the center. Today's heliocentric model places the________ at the center of the solar system.

Answers

Answer:

Earth

Sun

Explanation:

The heliocentric model opposes the geocentric model by placing the sun at the center of the solar system as opposed to the earth as it is with the geocentric model

MIDDLE SCHOOL

Which two phases of the water cycle are repeated in this process? A. evaporation and precipitation B. evaporation and condensation C. precipitation and transpiration D. condensation and precipitation

Answers

It Is A Evaporation And Precipitation

Answer:

a evaporation, condensation, precipitation

Explanation:

MIDDLE SCHOOL

Predicting How would the slope of the graph change if the cyclist
were accelerating at a greater
rate? At a lesser rate?

Answers

Answer:

The slope of the acceleration vs. force graph represents the reciprocal of the mass of the system.

Explanation:

HIGH SCHOOL

should your directions to a friend for traveling from one city to another include displacements or distances?Explain

Answers

Displacements because it includes direction since you want to lead your friend to the right place. If you only include distances then it's like which way should they go. They don't know if it's north, east, south or west. They also don't know if they should travel in a straight line or do they have to make a lot of turns
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