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olga2289 [7]
3 years ago
7

1.Two skaters, Evelyn and Lily, face each other on near frictionless ice. Evelyn has a mass of 57.4 kg, and Lily has a mass of 4

8.3 kg. Both are motionless until they push away with a force of 33 N. Then Evelyn has a velocity of 1.4 m/s. What is Lily's velocity
Physics
1 answer:
Elena L [17]3 years ago
3 0

Answer:

-1.67 m/s

Explanation:

We can solve this problem by using the law of conservation of momentum: in fact, since the system is isolated (no external forces, since the ice is frictionless), the total momentum of Evelyin and Lily must be conserved.

The total momentum before is zero, since they are both at rest:

p_i = 0

The total momentum after is:

p_f = mv+MV

where

m = 48.3 kg is Lily's mass

M = 57.4 kg is Evelyin's mass

V = 1.4 m/s is Evelyn's velocity

v is the Lily's velocity

Since momentum is conserved,

p_i=p_f

And so

0=mv+MV

Solving for v, we find Lily's velocity:

v=-\frac{MV}{m}=-\frac{(57.4)(1.4)}{48.3}=-1.67 m/s

And the negative sign indicates that her direction is opposite to Evelyn's direction.

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Answer:

Explanation:

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7 0
3 years ago
Round off to the nearest one (units place):
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Answer:

a

Explanation:

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According to the Doppler Effect, which statement is true about a sound as it approaches you and then moves away.
sukhopar [10]

Answer:

A) As the source approaches you, the waves are compressed so that the pitch of the noise increases.  

Explanation:

The Doppler Effect occurs when there is relative motion between an observer and the source of a wave. When this happens, there is an apparent shift in the frequency of the wave, as perceived by the observer. In particular, two situations can occur:

1- If the source of the wave is moving towards the observer, the waves are compressed, so that the wavelength of the wave decreases, and therefore the frequency (and so the pitch) increases

2- If the source of the wave is moving away from the observer, the waves are stretched, so that the wavelength of the wave increases, and therefore the frequency (and so the pitch) decreases

An example of Doppler Effect occurs when we hear the sound of the siren of an ambulance.

In this problem, the situation described is situation 1 (sound waves is approaching the observer), so according to the explanation above, the correct answer is

A) As the source approaches you, the waves are compressed so that the pitch of the noise increases.

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3 years ago
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8 0
2 years ago
The cue ball is deflected so that it makes an angle of 30.0° with its original direction of travel.
Alexus [3.1K]

Answer:

(a) θ= 43.89°

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u_{1} = 7.52\frac{m}{s}

Ball 2:

u_{2} = 0\frac{m}{s}

As the collision is elastic, it means that kinetic energy and momentum are conserved. Following that, we apply the law of conservation of energy and momentum:

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From conservation in y-direction, we get:

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From this, we solve this equation system and get the answers. Remember to add 30° to the angle obtained.

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