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PSYCHO15rus [73]
3 years ago
9

The velocity of a 200 kg object is changed from 5 m/s to 25 m/s in 50 seconds by an applied constant force.

Physics
1 answer:
hram777 [196]3 years ago
4 0
<h2>a) Change in momentum is 4000 kg m/s in the direction of motion</h2><h2>b) Magnitude of the force is 80 N</h2>

Explanation:

Force is given by rate of change of momentum.

Mass of object = 200 kg

Initial velocity = 5 m/s

Final velocity = 25 m/s

a) Change in momentum = 200 x 25 - 200 x 5

Change in momentum = 4000 kg m/s in the direction of motion

b) Time taken = 50 s

Rate of change of momentum = Change in momentum ÷ Time

Rate of change of momentum = 4000 ÷ 50

Rate of change of momentum = 80 N

Force = 80 N

Magnitude of the force is 80 N

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A weightlifter lifts a set of weights a vertical distance of 2.00m.If a constant net force of 350 N is exerted on the weights,wh
MrMuchimi

Answer:

<em>W=700 Joule</em>

Explanation:

<u>Physics Work </u>

Is the dot product of the force vector by the displacement vector

W=\vec F \cdot \vec r

When both the force and the displacements are pointed in the same direction, the formula reduces to its scalar version

W=F.d

The weightlifter is applying a net force of 350 N to lift the weights a distance of 2 m, thus the net work done is

W=350\ N\ .\ 2\ m=700\ Joule

4 0
3 years ago
2. A rocket blasts off vertically from rest on the launch pad with a constant upward acceleration of 2.5 . At 30.0 s after blast
harina [27]

Answer:

a)The highest point reached by the rocket is 1412 m

b)The rocket crashes after 54.7 s

Explanation:

Hi there!

The equations of height and velocity of the rocket are the following:

h = h0 + v0 · t + 1/2 · a · t² (while the engines work).

h = h0 + v0 · t + 1/2 · g · t² (when the rocket is in free fall).

v = v0 + a · t (while the engines work).

v = v0 + g · t (when the rocket is in free fall).

Where:

h = height of the rocket at a time t.

h0 = initial height of the rocket.

v0 = initial velocity.

t = time.

a = acceleration due to the engines.

g = acceleration due to gravity (-9.8 m/s² considering the upward direction as positive).

v = velocity of the rocket at a time t.

First, let's find the velocity and height reached by the rocket until the engines fail:

h = h0 + v0 · t + 1/2 · a · t²

Let's set the origin of the frame of reference at the launching point so that h0 = 0. Since the rocket starts from rest, v0 = 0. So after 30.0 s the height of the rocket will be:

h = 1/2 · a · t²

h = 1/2 · 2.5 m/s² · (30.0 s)²

h = 1125 m

Now let's find the velocity of the rocket at t = 30.0 s:

v = v0 + a · t (v0 = 0)

v = 2.5 m/s² · 30.0 s

v = 75 m/s

After 30.0s the rocket will continue to ascend with a velocity of 75 m/s. This velocity will be gradually reduced due to the acceleration of gravity. When the velocity is zero, the rocket will start to fall. At that time, the rocket is at its maximum height. So, let's find the time at which the velocity of the rocket is zero:

v = v0 + g · t

0 = 75 m/s - 9.8 m/s² · t (v0 = 75 m/s because the rocket begins its free-fall motion with that velocity).

-75 m/s / -9.8 m/s² = t

t = 7.7 s

Now, let's find the height of the rocket 7.7 s after the engines fail:

h = h0 + v0 · t + 1/2 · g · t²

The rocket begins its free fall at a height of 1125 m and with a velocity 75 m/s, then, h0 = 1125 m and v0 = 75 m/s:

h = 1125 m + 75 m/s · 7.7 s - 1/2 · 9.8 m/s² · (7.7 s)²

h = 1412 m

The highest point reached by the rocket is 1412 m

b) Now, let's calculate how much time it takes the rocket to reach a height of zero (i.e. to crash) from a height of 1412 m.

h = h0 + v0 · t + 1/2 · g · t² (v0 = 0 because at the maximum height the velocity is zero)

0 = 1412 m - 1/2 · 9.8 m/s² · t²

-1412 m / -4.9 m/s² = t²

t = 17 s

The rocket goes up for 30.0 s with an acceleration of 2.5 m/s².

Then, it goes up for 7.7 s with an acceleration of -9.8 m/s².

Finally, the rocket falls for 17 s with an acceleration of -9.8 m/s²

The rocket crashes after (30.0 s + 7.7 s + 17 s) 54.7 s

6 0
3 years ago
Explain why your senses would lead you to believe that the Earth is center of the universe
ASHA 777 [7]

<u>Answer:</u>

This is due to the apparent movement of the celestial bodies, seen from an observer centered on the Earth. If we did not have knowledge of the advances of science and the latest discoveries, we would think that the Earth is the center of the universe.

For example, for an observer on Earth as a reference system, the Sun moves every day from east to west, as do the planets and all the stars that we observe at night, which leads the observer to believe that those in motion are these bodies outside in the sky while the earth is still and fixed in the universe.

Keep in mind that this theory of geocentrism was widely accepted for a long time in antiquity, until the astronomer Nicolaus Copernicus proposed a completely different and opposite idea, heliocentrism (universe centered on the Sun).

However, at present it is known and accepted that the universe has no center, that the Earth revolves around the Sun and that in reality all the bodies of the universe are in movement.

5 0
3 years ago
Whats a meteroligist
Dvinal [7]

Answer:

a meteorologist is a specialist who studies processes in the earth's atmosphere that cause weather conditions  

Explanation:

4 0
3 years ago
14. Which type of heat transfer (caused by uneven heating) moves air and water around the earth and creates weather? Question 14
Katena32 [7]

Answer: convection

Explanation:

There are three ways in which the heat (thermal energy) transfer occurs:  

<u>1. By Conduction</u>, when the transmission is by the direct contact.  

<u>2. By Convection</u>, heat transfer in fluids (like water or the air, for example).  

<u>3. By Radiation</u>, by the electromagnetic waves (they can travel through any medium and in vacumm)

In this especific case, we will talk about convection, which occurs when the hottest parts of a fluid ascend to the coldest zones, generating a continuous circulation of the fluid (better known as convective current) transmitting heat to the cold zones by decreasing the density caused by the increase in temperature.

This is what happens in Earth, when the convective heat transfer occurs, through the movement of groups of molecules that make up the medium (water and air in this situation) changing with temperature and creating the weather .  

7 0
3 years ago
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