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VashaNatasha [74]
2 years ago
7

A train travels 190km in 3.0 hours and then 120 km in 2.0 hours. What is it’s average speed ?

Physics
1 answer:
xxMikexx [17]2 years ago
6 0

Answer:

60 km/h

Explanation:

Simplify the speed:

120÷2=60

Hence, the average speed is 60 km/h.

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The primary purpose of a mirror is to _________ light rays.
Effectus [21]
a. reflect (I found this using prior knowledge and process of illumination it can't be absorb cuz you wouldn't see anything it can't be refract because it doesn't reverse the image and it isn't transmit )
8 0
3 years ago
The pan flute is a musical instrument consisting of a number of closed-end tubes of different lengths. When the musician blows o
IgorLugansk [536]

Answer:

  f = 276.6 Hz

Explanation:

This musical instrument can be approximated to a tube system where each tube has one end open and the other closed.

In the closed part there is a node and in the open part a belly or antinode. Therefore the wavelength is

          L = λ/ 4

speed is related to wavelength and frequency

          v = λ f

          λ = v / f

we substitute

          L = v / 4f

          f = v / 4L

the speed of sound at 20ºC is

          v = 343 m / s

let's calculate

          f = \frac{343 }{4 \ 0.31}

          f = 276.6 Hz

4 0
3 years ago
Define Newton’s three laws of motion and how they apply to everyday situations.
son4ous [18]
<span>1. By Ilkka Cheema<span><span>2. </span>Newton’s 1st Law  The first law of motion sates that an object will not change its speed or direction unless an unbalanced force (a force which is distant from the reference point) affects it. Another name for the first law of motion is the law of inertia. If balanced forces act on an object it doesn’t accelerate or change direction. This means it doesn’t change its velocity and it doesn’t have momentum.</span><span><span>3. </span>Examples of Newton’s 1st Law  If you slide a hockey puck on ice, eventually it will stop, because of friction on the ice. It will also stop if it hits something, like a player’s stick or a goalpost.  If you kicked a ball in space, it would keep going forever, because there is no gravity, friction or air resistance going against it. It will only stop going in one direction if it hits something like a meteorite or reaches the gravity field of another planet.  If you are driving in your car at a very high speed and hit something, like a brick wall or a tree, the car will come to an instant stop, but you will keep moving forward. This is why cars have airbags, to protect you from smashing into the windscreen.</span><span><span>4. </span>Newton’s 2nd Law  The second law of motion states that acceleration is produced when an unbalanced force acts on an object (mass). The more mass the object has the more net force has to be used to move it.</span><span><span>5. </span>Examples of Newton’s 2nd Law  If you use the same force to push a truck and push a car, the car will have more acceleration than the truck, because the car has less mass.  It is easier to push an empty shopping cart than a full one, because the full shopping cart has more mass than the empty one. This means that more force is required to push the full shopping cart.</span><span><span>6. </span>Newton’s 3rd Law The third law of motion sates that for every action there is a an equal and opposite reaction that acts with the same momentum and the opposite velocity.</span><span><span>7. </span>Examples of Newton’s 3rd Law  When you jump off a small rowing boat into water, you will push yourself forward towards the water. The same force you used to push forward will make the boat move backwards.  When air rushes out of a balloon, the opposite reaction is that the balloon flies up.  When you dive off of a diving board, you push down on the springboard. The board springs back and forces you into the air.</span></span>
3 0
3 years ago
Now the elevator is moving downward with a velocity of v = -2.8 m/s but accelerating upward with an acceleration of a = 5.5 m/s2
borishaifa [10]

Answer:

160.75 N

Explanation:

The downward velocity has no effect on the force situation, it is only changes in velocity (plus, of course, gravity, which is always there) that require a force. At constant velocity, the bottom spring s_3 is supporting its mass m_3 to balance gravity.

As the elevator slows, though, it also ends up slowing down the spring arrangement, too. However, because the stretching takes time, it means that some damped harmonic motion will be set up in the spring chain.

When the motion has finally damped out, the net force the bottom spring s3 exerts on m3 has two components--that of gravity and of the deceleration of the elevator:

F_3net = m3 * (g + a) = 10.5×(9.81+5.5)= 10.5×15.31= 160.75 N

5 0
3 years ago
Thường ngày an đi bộ từ nhà đến trường mất 15 phút biết quãng đường từ nhà đến trường dài 1.5 km tính vận tốc đi thường ngày của
DedPeter [7]

Answer:

Speed in kilometer/hour = 6 kilometer / hour

Explanation:

Given;

Time taken to cover distance = 15 minute = 15 /60 = 0.25 hour

Distance of school = 1.5 kilometer

Find:

Speed in kilometer/hour

Computation:

Speed in kilometer/hour = Distance / Time

Speed in kilometer/hour = Distance of school / Time taken to cover distance

Speed in kilometer/hour = 1.5 / 0.25

Speed in kilometer/hour = 6 kilometer / hour

7 0
3 years ago
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