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olga55 [171]
3 years ago
9

On an ice skating rink, a girl of mass 50 kg stands stationary, face to face with a boy of mass 80 kg. The children push off of

one another, and the boy moves away with a velocity of 3 m/s. What is the final velocity of the girl? â€"1. 9 m/s 1. 9 m/s â€"4. 8 m/s 4. 8 m/s.
Physics
1 answer:
sasho [114]3 years ago
5 0

The velocity of the girl is  -4.8 m/s.

Using the principle of conservation of linear momentum, The total momentum of  bodies before and after collision is constant. Since the two objects are stationary, the initial momentum of each body is zero.

Thus;

0 = (80 × 3) + (50 × v)

0 = 240 + 50 v

-240 = 50 v

v = -240/50

v = -4.8 m/s

Note that the negative sign shows that the velocity of the girl is in opposite direction that that of the girl.

Learn more about momentum: brainly.com/question/904448

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An empty 2,500 kg train car is headed northbound at a velocity of 5 m/s. Ahead of the first car, an empty 1,500 kg car is headed
Tema [17]

Let the mass of 2500 kg car be m_1 and it's velocity be v_1 and the mass of 1500 kg car be m_2 and it's velocity be v_2 .

After the bumping the mass be M and it's velocity be V.

     By law of conservation of momentum we have

                   m_1v_1+m_2v_2 = MV

                    2500 * 5 + 1500 * 1=4000 * V

                    V = 14000/4000 = 7/2 = 3.5 m/s

So the velocity of the two-car train = 3.5 m/s

9 0
3 years ago
A small bug is lying resting when nine ants simultaneously ambush it and begin pulling it in different directions. They are each
xxMikexx [17]

Answer: The bug will remain motionless

Explanation:

According to Newton's first Law of Motion (sometimes called Law of Inertia):

<em>An object at rest or describing a uniform straight line motion (moving at constant velocity), will remain at rest or moving unless an external force is applied to it and changes its state of rest or motion. </em>

In other words:

An object or body will keep its state of motion until an external force changes its state

This means that objects tend to remain in its state of motion, and is the definition of the inertia, as well.

In addition, according to his law, an object in rest can be in equilibrium (net force equals to zero), and a moving object can also be in equilibrium, as long as it keeps a constant velocity.

<h2>This is why the bug, which is at rest will remain at rest, although the ants are simultaneously pulling it in different directions, since the resultant of all these forces is zero.</h2>
4 0
3 years ago
Rearrange the momentum equation to solve for speed. Show all work.
nasty-shy [4]

Definition:                   Momentum  =  (mass) x (speed)


OK. Here we go.
Watch closely:


Divide each side        
by  'mass' :                  <span>Momentum / mass  =  Speed </span>


Did you follow that ?

3 0
3 years ago
Ultraviolet light from a distant star is traveling at 3.0 × 108 m/s. how long will it take for the light to reach earth if it mu
castortr0y [4]

Given speed and the distance that must be covered, the time it will take the ultraviolet light to reach the earth is 3.7 × 10⁴ hours.

<h3>What is Speed?</h3>

Speed is simply referred to as distance traveled per unit time.

Mathematically, Speed = Distance ÷ time.

Given the data in the question;

  • Speed of the Ultraviolet light c = 3.0 × 10⁸m/s = 1.08 × 10⁹km/h
  • Distance it must cover d = 4.0 × 10¹³km
  • Time elapsed t = ?

We substitute our given values into the expression above.

Speed = Distance ÷ time

1.08 × 10⁹km/h = 4.0 × 10¹³km ÷ t

t = 4.0 × 10¹³km ÷ 1.08 × 10⁹km/h

t = 3.7 × 10⁴ hrs

Therefore, given speed and the distance that must be covered, the time it will take the ultraviolet light to reach the earth is 3.7 × 10⁴ hours.

Learn more about speed here: brainly.com/question/7359669

#SPJ4

5 0
2 years ago
How is tidal energy obtained
yKpoI14uk [10]
Under water turbans that are placed at the above to middle of the ocean they are used to capture kinetic motion
7 0
4 years ago
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