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sveta [45]
3 years ago
15

Please need help on this

Physics
1 answer:
ale4655 [162]3 years ago
7 0

the answer is the third one down

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n the railroad accident, a boxcar weighting 200 kN and traveling at 3 m/s on horizontal track slams into a stationary caboose we
USPshnik [31]

Answer:

ΔK = -6 10⁴ J

Explanation:

This is a crash problem, let's start by defining a system formed by the two trucks, so that the forces during the crash have been internal and the moment is preserved

initial instant. Before the crash

        p₀ = m v₁ + M 0

final instant. Right after the crash

        p_f = (m + M) v

        p₀ = p_f

        mv₁ = (m + M) v

        v = \frac{m}{m+M} \  v_1

     

we substitute

        v = \frac{20}{20+40}   3

        v = 1.0 m / s

having the initial and final velocities, let's find the kinetic energy

        K₀ = ½ m v₁² + 0

        K₀ = ½ 20 10³ 3²

        K₀ = 9 10⁴ J

        K_f = ½ (m + M) v²

        K_f = ½ (20 +40) 10³  1²

        K_f = 3 10⁴ J

the change in energy is

       ΔK = K_f - K₀

       ΔK = (3 - 9) 10⁴

       ΔK = -6 10⁴ J

The negative sign indicates that the energy is ranked in another type of energy

7 0
3 years ago
100 kw of power is delivered to the other side of a city by a pair of power lines with the voltage difference of 13014.1 v.
FinnZ [79.3K]
A) The power delivered to the lines is
P_{in}= 100 kW=1 \cdot 10^5 W
And the voltage at which the lines work is
V=13014.1 V
Since the power delivered is the product between the voltage and the current:
P=VI
We can find the current flowing in the lines:
I= \frac{P}{V}= \frac{1 \cdot 10^5 W}{13014.1 V}=7.68 A

b) The voltage change along each line can be found by using Ohm's law:
\Delta V = IR = (7.68 A)(10 \Omega)=76.8 V

c) The power wasted as heat along each line is given by:
P_d = I^2 R = (7.68 A)^2 (10 \Omega) = 590 W
And since we have 2 lines, the total power wasted as heat in both lines is
P_d = 2 \cdot 590 W=1180 W
6 0
3 years ago
A bullet of mass of 50g is moving with the velocity of 200km/h .calculate the kinetic energy of the bullet .​
Evgen [1.6K]
Not sure if this it completely right but here’s what I got: 77.16050617284 J
6 0
3 years ago
Read 2 more answers
How do the stars die?
mestny [16]

A star’s death also depends on its mass. The most massive stars quickly exhaust their fuel supply and explode in core-collapse supernovae, some of the most energetic explosions in the universe. A supernova’s radiation can easily (if only briefly) outshine the rest of its host galaxy. The remnant stellar core will form a neutron star or a black hole, depending on how much mass remains. If the core contains between 1.44 and 3 solar masses, that mass will crush into a volume just 10 to 15 miles wide before a quantum mechanical effect known as neutron degeneracy pressure prevents total collapse. The exact upper limit on a neutron star mass isn’t known, but around 3 solar masses, not even neutron degeneracy pressure can combat gravity’s inward crush, and the core collapses to form a black hole.

5 0
4 years ago
Which statement best describes the equation CaCO3 + 2HCl → CaCl2 + CO2 + H2O? CaCO3 is a reactant; it is present before the reac
Marat540 [252]

Answer:

CaCl2 is a reactant

Explanation:

Calcium carbonate (CaCO3) is a reagent, it is found on the left side, what is found on the right side are the products.

6 0
3 years ago
Read 2 more answers
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