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Eva8 [605]
2 years ago
13

Also need help with 20 & 21 please

Physics
2 answers:
SSSSS [86.1K]2 years ago
5 0
Number 20 is B and 21 is C
Hoochie [10]2 years ago
5 0
A density is a physical change
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butalik [34]

B. +Q, + W are the correct sign

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An observer sees a full moon in the night sky. What will the Moon's phase be 10 days later?
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I'm pretty sure the moon would be a crescent within the 10 day period because it takes about 28 days for the moon to go through the different stages.
5 0
3 years ago
Identify the conditions for an elastic collision in a closed system. Check all that apply.
s344n2d4d5 [400]

Answer:

In an elastic collision:

  • There is no external net force acting. Thus, Momentum before and after collision is equal. Momentum remains conserved.
  • Total energy always remains conserved as energy cannot be created nor destroyed. It can change from one form to another.
  • There is no lost due to friction in elastic collision. So the kinetic energy is also conserved.
  • Velocities may change after collision. If the masses are equal, the velocities interchange.

When one object is stationary:

Final velocity of object 1:

v₁ = (m₁ - m₂)u₁/(m₁ +m₂)

Final velocity of object 2:

v₂ = (2 m₁ u₁)/(m₁+m₂) =

  • Objects do not stick together in elastic collision. They stick together in inelastic collision.
  • One object may be stationary before the elastic collision.

Thus, conditions for an elastic collision:

  • Energy is conserved.
  • Velocities may change.
  • Momentum is conserved.
  • Kinetic energy is conserved.
  • One object may be stationary before the elastic collision.
7 0
3 years ago
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Two coils, held in fixed positions, have a mutual inductance of M = 0.0034 H. The current in the first coil is I(t) = I0sin(ωt),
tiny-mole [99]

Answer:

ε₂ =2.63 V

Explanation:

given,

M = 0.0034 H

I (t) = I₀ sin (ωt)

I (t) = 5.4 sin (143 t)

\dfrac{d i(t)}{dt} = \dfrac{d}{dt}(5.4 sin (143 t))

\dfrac{d i(t)}{dt} =143 \times 5.4 cos (143 t)

magnitude of the induced emf in the second coil

ε₂ =M\dfrac{di}{dt}

ε₂ =0.0034\times 143 \times 5.4 cos (143 t)

for maximum emf

cos (143 t) = 1

ε₂ =0.0034\times 143 \times 5.4

ε₂ =2.63 V

3 0
3 years ago
A child lifts a 5.0-newton toy to a height of 0.50 meters. How much work is done on the toy?
natali 33 [55]
Work done=mgh
W=force*height
W=5N*0.50mts
W=2.5joule
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3 years ago
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