Formula for height
<span> r(t) = a/2 t² + v₀ t + r₀
</span><span> where
</span><span> a = acceleration = -32 ft/sec² (gravity)
</span><span> v₀ = initial velocity
</span><span> r₀ = initial height
</span><span> r(t) = -16t² + v₀ t + r₀
</span> <span>Tomato passes window (height = 450 ft) after 2 seconds:
</span><span> r(2) = 450
</span><span> -16(4) + v₀ (2) + r₀ = 450
</span><span> r₀ = 450 + 64 - 2v₀
</span><span> r₀ = 514 - 2v₀
</span><span> Tomato hits the ground (height = 0 ft) after 5 seconds:
</span><span> r(5) = 0
</span><span> -16(25) + v₀ (5) + r₀ = 0
</span> r<span>₀ = 16(25) - 5v₀
</span><span> r₀ = 400 - 5v₀
</span><span>
r₀ = 514 - 2v₀ and r₀ = 400 - 5v₀
</span> <span>514 - 2v₀ = 400 - 5v₀
</span><span> 5v₀ - 2v₀ = 400 - 514
</span> <span>3v₀ = −114
</span><span> v₀ = −38
</span><span> Initial velocity = −38 ft/sec (so tomato was thrown down)
</span><span> (initial height = 590 ft) </span>
Answer:
the answer is d
Explanation:
basically the reason i think this is the answer is because the answer that i picked in this scenario to me seems like the right one and it it the one i picked on the quiz that seemed like the right one to me and i am smart and cool and awesome
subscibe to my channel jacknjellify
Since waves are moving, we define frequency as the number of waves that pass a given point in a specified unit of time. The unit commonly used is Hertz which is the number of wave cycles that pass a point in one second.
(a) The efficiency of an engine is defined as the ratio between the work done by the engine and the heat it takes in:
The engine in this problem does a work of
and it takes in
of heat, therefore its efficiency is
(b) The heat taken by the machine is 4000 J; of this amount of heat, only 1100 J are converted into useful work. This means that the rest of the heat is wasted. Therefore, the wasted heat is the difference between the heat in input and the work done by the engine:
Answer:
λ = 548.7 nm
Explanation:
Hi!
First we want to know how much energy we need to remove 1 electron from the surface of the solid:
218.1 kJ/mol => 218 100 J / (6.022 x 10^23) electrons
= 3.621 x 10^-19 J/electron
That is we need 3.621 x 10^-19 J to remove one electron
Now we can calculate the wavelength that a photon must have in order to have this energy:
E = (hc) / λ
λ = (hc) / Ε
where
h = 6,626070150(69) ×10 -34 Js (wikipedia)
c = 3 x10^8 m/s
hc = 1.987 x 10^-25 Jm
Therefore:
λ = ( 1.987 x 10^-25 /3.621 x 10^-19 ) m = 5.487 x 10^-7 m
λ = 548.7 nm
