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olga55 [171]
2 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]2 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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Using Newton's third law of motion, explain what happens when you let an untied balloon go.
mash [69]

Answer:

balloon pushes you back

Explanation:

3rd Law: Every action has an equal and opposite reaction

So, when you let go of the balloon it's pushed forward so the balloon pushes you back

7 0
3 years ago
Read 2 more answers
Review. From a large distance away, a particle of mass 2.00 g and charge 15.0σC is fired at 21.0 i^ m/s straight toward a second
MissTica

(a)

Determine the system's initial configuration at ri = infinite particle separation and the system's final configuration at the point of closest approach.

Since the two-particle system is not being affected by any outside forces, we may treat it as an isolated system for momentum and use the momentum conservation law.

m1v1 + m1v2 = (m1+m2)v

The second particle's starting velocity is zero, so:

m1v1  = (m1+m2)v

After substituting the values we get,

v = 6i m/s

(b)

Since the two particle system is also energy-isolated, we may use the energy-conservation principle.

dK + dU = 0

Ki +Ui = Kf + Uf

Substituting the values,

1/2m1v1^2i + 1/2 m2v2^2i + 0 = 1/2m1v1^2f + 1/2m2v2^2f +ke q1q2/rf

The second particle's initial speed is 0 (v2 = 0). Additionally, both the first and second particle's final velocity have the same value, v. Put these values in place of the preceding expression:

1/2m1v1^2i  = 1/2m1v1^2 + 1/2m2v2^2 +ke q1q2/rf

After solving we get,

rf = 2ke q1q2 / m1v1^2 - (m1+m2)v^2

Substituting the values we get,

rf = 3.64m

(c)

v1f = (m1-m2 / m1 + m2) v1i

v1f  = -9i m/s

(d)

v2f =  (2m1/ m1 +m2) v1i

After substituting the values,

v2f = 12i m/ s

Question :

Review. From a large distance away, a particle of mass 2.00 g and charge 15.0 \muμC is fired at 21.0 m/s straight toward a second particle, originally stationary but free to move, with mass 5.00 g and charge 8.50 \muμC. Both particles are constrained to move only along the x axis. (a) At the instant of closest approach, both particles will be moving at the same velocity. Find this velocity. (b) Find the distance of closest approach. After the interaction, the particles will move far apart again. At this time, find the velocity of (c) the 2.00-g particle and (d) the 5.00-g particle. \hat{i}

To learn more about  momentum conservation law click on the link below:

brainly.com/question/7538238

#SPJ4

5 0
2 years ago
Which is the result of using a machine?
Eddi Din [679]
Correct Answers is A.

The machines gives us some mechanical advantage. This means the mechanical average makes the work output greater than the work input
Simple most example is a lever. The force applied is smaller and the output work is larger as compared to input.

Option B cannot be true, as there must be a force to get some work done.
Option C and D are inverse of what a machine is designed for. A small force can be exerted through a large distance to have a large force exerted through a small distance. Common Example of this principle is a screw opener. 
3 0
3 years ago
To lift a load of 100 kg a distance of 1 m an effort of 25 kg must be applied over an inclined plane of length 4 m. What must be
andreyandreev [35.5K]
Work = force * distance.
We must produce twice as much energy as we are lifting the weight twice as high.
But we are not increasing the force so we must increase the length of the ramp ( distance ) instead.
The new length will be twice as great as the previous length.
So 8 metres is required. 


25 kg * 8 m = work = 100 kg * 2 m
7 0
3 years ago
An electromagnetic wave is propagating in the positive x direction. at a given moment in time, the magnetic field at the origin
antiseptic1488 [7]

Since in an electromagnetic wave the electric and magnetic fields are perpendicular to each other and perpendicular to the direction of motion, the electric field has to point in the z direction.

6 0
3 years ago
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