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Tpy6a [65]
3 years ago
11

a backpack has a mass of 8 kg. it is lifted and given 54.9 J of gravitational potential energy. how high is is lifted? accelerat

ion due to gravity is g=9.8 m/s^2.
Physics
1 answer:
dalvyx [7]3 years ago
8 0
P=mgh
h=P/mg
h=(54.9)/(8*9.8)= 0.7m
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red light from a He-Ne laser is at 590.5 nm in the air. it is fired at an angle of 31.0 to horizontal at a flat transparent crys
Darina [25.2K]

Answer:

7374.4

Explanation:

I took the test

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5 0
2 years ago
(15pts) A hungry 12.0 kg fish is coasting from west to east at 75 cm/s when it suddenly swallows a 1 kg fish swimming towards it
faust18 [17]

Answer:

The speed of the big fish after swallowing the small fish is 0.38 m/s.

Explanation:

Consider west to east direction as positive and the opposite direction as negative.

Given:

Mass of big fish (m₁) = 12.0 kg

Initial velocity of big fish (u₁) = 75 cm/s = 0.75 m/s

Mass of small fish (m₂) = 1 kg

Initial velocity of small fish (u₂) = -4 m/s (Direction is opposite to u₁)

After swallowing the small fish, both the fishes move together with same velocity. Let the velocity be 'v'.

So, as there are no effects of drag or any other forces, the given scenario can be considered as a case of inelastic collision where the objects move together with same velocity after collision.

The momentum is conserved in inelastic collision. Therefore,

Initial momentum of the fishes = Final momentum of the fishes

m_1u_1+m_2u_2=(m_1+m_2)v\\\\v=\dfrac{m_1u_1+m_2u_2}{m_1+m_2}

Now, plug in the given values and solve for 'v'. This gives,

v=\frac{12.0\times 0.75+1\times (-4)}{12.0+1}\\\\v=\frac{9-4}{13}\\\\v=\frac{5}{13}=0.38\ m/s

Therefore, the speed of the big fish after swallowing the small fish is 0.38 m/s

3 0
3 years ago
Thiết bị trao đổi nhiệt ngược chiều, nhiệt độ chất lỏng nóng vào là 310°C, ra là 115°c. Nhiệt độ chất lỏng lạnh vào là 25°c và r
Vika [28.1K]

Answer: 129.5 m

Explanation:

310 + 115 + 25 + 68 = 518

518 / 4 = 129.5 m

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5 0
3 years ago
Pressure is about 1000 hPa at sea level and about 500 hPa at an altitude of 5.5 km. Why doesn’t this vertical pressure gradient
saul85 [17]

Answer:

A. The upward pressure gradient force is balanced by gravity.

Explanation:

A. is correct because the pressure difference is actually generated by gravity. As in the following formula for the pressure at different points:

p = p_0 + \rho g h

where p, p_0 are the pressure at 2 points, ρ is the density of the fluid, g is the gravitational constant, and h is the height difference.

B is incorrect because friction in air is too small to make an effect.

C is incorrect because the Coriolis force is horizontal, not vertical.

D is incorrect because a difference of 500 hPa = 50000 Pa, this is half of the atmospheric pressure.

E is incorrect because temperature cannot generate force.

6 0
3 years ago
Calculate the KE of a 3.1 kg toy cart that moves at 4.8 m/s. Calculate the KE of the same cart at twice the speed.
lisov135 [29]
When v= 4.8 m/s:

E.K=mv²/2
      =3,1(4.8)²/2
      =35.712J

when v= 2(4.8):

E.K=mv²/2
      =3.1(9.6)²/2
      =142.848J


4 0
3 years ago
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