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Vlad [161]
2 years ago
7

A brush fire is burning on a rock ledge on one side of a ravine that is 25 m wide. A fire truck sits on the opposite side of the

ravine at an elevation 4.5 m above the burning brush. The fire hose nozzle is aimed 35∘ above horizontal, and the firefighters control the water velocity by adjusting the water pressure. Because the water supply at a wilderness fire is limited, the firefighters want to use as little as possible.
At what speed should the stream of water leave the hose so that the water hits the fire on the first shot?
Physics
1 answer:
Ierofanga [76]2 years ago
8 0

Answer:

v_o = 30.5 m/s

Explanation:

Height of the hose pipe is given as

y = 4.5 m

horizontal distance is given as

x = 25 m

angle of elevation is given as 35 degree with the horizontal

now we know that the horizontal distance moved is given as

x = (v_ocos35) t

y = 4.5 + (v_o sin35) t - \frac{1}{2}(9.8)t^2

now we have

25 = v_o(0.82)t

also we have

0 = 4.5 + 0.57 v_o t - 4.9 t^2

0 = 4.5 + (0.57)(0.82) - 4.9 t^2

t = 1.00 s

so we have

v_o = 30.5 m/s

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A man is standing on the edge of a 20.0 m high cliff. He throws a rock horizontally with an initial velocity of 10.0 m/s. How lo
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Answer:

t = 4.08 s

R = 40.8 m

Explanation:

The question is asking us to solve for the time of flight and the range of the rock.

Let's start by finding the total time it takes for the rock to land on the ground. We can use this constant acceleration kinematic equation to solve for the displacement in the y-direction:

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We have these known variables:

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  • a_y = -9.8 m/s²
  • Δx_y = -20 m

And we are trying to solve for t (time). Therefore, we can plug these values into the equation and solve for t.

  • -20 = 0t + 1/2(-9.8)t²
  • -20 = 1/2(-9.8)t²
  • -20 = -4.9t²
  • t = 4.08 sec

The time it takes for the rock to reach the ground is 4.08 seconds.

Now we can use this time in order to solve for the displacement in the x-direction. We will be using the same equation, but this time it will be in terms of the x-direction.

List out known variables:

  • v_0 = 10 m/s
  • t = 4.08 s
  • a_x = 0 m/s

We are trying to solve for:

  • Δx_x = ?

By using the same equation, we can plug these known values into it and solve for Δx.

  • Δx = 10 * 4.08 + 1/2(0)(4.08)²
  • Δx = 10 * 4.08
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The rock lands 40.8 m from the base of the cliff.

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A bird flew16 km west in 5 hours, then flew 20 km east in 6 hours. what was the birdâs velocity?
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Answer:

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Explanation:

correct on edge :)

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