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NISA [10]
3 years ago
11

A boxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. The moving boxcar colli

des and links with the stationary cars and they all move off together along the track. What is the final speed of the cars immediately after the collision? (You may take the mass of each boxcar to be 18,537 kg.)
Physics
1 answer:
olga2289 [7]3 years ago
6 0

Answer:

2 m/s

Explanation:

Momentum is conserved:

mv = MV

where m is mass of the boxcar, v is its initial velocity, M is the mass of all six box cars, and V is the final velocity.

v = 12 m/s, and M = 6m, so:

m (12 m/s) = 6m V

12 m/s = 6V

V = 2 m/s

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You are trying to overhear a juicy conversation, but from your distance of 20.0 m , it sounds like only an average whisper of 30
12345 [234]

Answer:

r₂ = 0.2 m

Explanation:

given,

distance = 20 m

sound of average whisper = 30 dB

distance moved closer = ?

new frequency = 80 dB

using formula

\beta = 10 log(\dfrac{I_1}{I_0})

   I₀ = 10⁻¹² W/m²

now,

30 = 10 log(\dfrac{I_1}{10^{-12}})

\dfrac{I_1}{10^{-12}}= 10^3

I_1= 10^{-8}\ W/m^2

to hear the whisper sound = 80 dB

80 = 10 log(\dfrac{I_2}{10^{-12}})

\dfrac{I_2}{10^{-12}}= 10^8

I_2= 10^{-4}\ W/m^2

we know intensity of sound is inversely proportional to square of distances

\dfrac{I_1}{I_2}=\dfrac{r_2^2}{r_1^2}

\dfrac{10^{-8}}{10^{-4}}=\dfrac{r_2^2}{20^2}

10^{-4}=\dfrac{r_2^2}{20^2}

  r₂ = 0.2 m

6 0
3 years ago
A particle has a charge of -4.25 nC.
SpyIntel [72]

Answer:

-611.32 N/C

0.43723 m

Explanation:

k = Coulomb constant = 8.99\times 10^{9}\ Nm^2/C^2

q = Charge = -4.25 nC

r = Distance from particle = 0.25 m

Electric field is given by

E=\dfrac{kq}{r^2}\\\Rightarrow E=\dfrac{8.99\times 10^9\times -4.25\times 10^{-9}}{0.25^2}\\\Rightarrow E=-611.32\ N/C

The magnitude is 611.32 N/C

The electric field will point straight down as the sign is negative towards the particle.

E=\dfrac{kq}{r^2}\\\Rightarrow r=\sqrt{\dfrac{kq}{E}}\\\Rightarrow r=\sqrt{\dfrac{8.99\times 10^9\times 4.25\times 10^{-9}}{13}}\\\Rightarrow r=1.71436\ m

The distance from the electric field is 1.71436 m

4 0
4 years ago
Read 2 more answers
During each cycle, a refrigerator ejects 610 kJ of energy to a high-temperature reservoir, and takes in 505 kJ of energy from a
jenyasd209 [6]

Answer

A. the work done on the refrigerant in each cycle is 105kJ

B the coefficient of performance of the refrigerator is 4.8

Explanation

Given data

Work done at high temperature T2 Qh=610kJ

Work done at low temperature T1 Ql=505kJ

We know that the net work done by the refrigerator is expressed as

Wnet= Qh-Ql

=610-505

=105kJ

Also we know that the coefficient of performance is expressed as

COP= Ql/Wnet

COP= 505/105

= 4.8

8 0
3 years ago
why can scientists ignore the forces of attraction between particles in a gas under ordinary conditions?
Anna35 [415]
<span>The particles in a gas are apart and moving fast, so the forces of attraction are too weak to have a noticeable effect.</span>
5 0
3 years ago
Read 2 more answers
How many motions variables do each of kinematic equations have
Leni [432]
The answer would be 4, each kinetic equation has 4 variables
3 0
3 years ago
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