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3 years ago

If the window is 11 m above the ground, find the time the stone is in flight.

1 answer:

5 0

d=vi*t+(1/2)gt²

d=11 m
g=9.8 m/s²
vi=0 m/s

11 m=0 m/s*t+(1/2)9.8 m/s²t²
11 m=4.9 m/s²t²
t²=11 m / 4.9 m/s²
t=√(11 m / 4.9 m/s²)=1.489... s≈1.5 s

Answer: the time the sone is in flight is 1.5 s

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If you exert a force of 100.0 N to lift a box a distance of 0.5 m, how much work do you do? 200 J 400 J 50 J 26 J

jeyben [28]

Work = force x distance
= 100N (force) x 0.5m (distance)
= 50J

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3 years ago

An electron in the n = 5 level of an h atom emits a photon of wavelength 1282.17 nm. to what energy level does the electron move

lions [1.4K]

This is an interesting (read tricky!) variation of Rydberg Eqn calculation.
Rydberg Eqn: 1/λ = R [1/n1^2 - 1/n2^2]
Where λ is the wavelength of the light; 1282.17 nm = 1282.17×10^-9 m
R is the Rydberg constant: R = 1.09737×10^7 m-1
n2 = 5 (emission)
Hence 1/(1282.17 ×10^-9) = 1.09737× 10^7 [1/n1^2 – 1/25^2]
Some rearranging and collecting up terms:
1 = (1282.17 ×10^-9) (1.09737× 10^7)[1/n2 -1/25]
1= 14.07[1/n^2 – 1/25]
1 =14.07/n^2 – (14.07/25)
14.07n^2 = 1 + 0.5628
n = √(14.07/1.5628) = 3

8 0

3 years ago

Read 2 more answers

What happens to a sheet of copper as kinetic energy of copper molecules decrease

liberstina [14]

First is melts then it expands next it gets cooler Finally it gains ener. Hope this helps you out.

8 0

3 years ago

Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. The scale reads 830 N for the first 3.8 s after the eleva

Delicious77 [7]

Answer:

v= 4.0 m/s

Explanation:

When standing on the bathroom scale within the moving elevator, there are two forces acting on Henry's mass: Normal force and gravity.
Gravity is always downward, and normal force is perpendicular to the surface on which the mass is located (the bathroom scale), in upward direction.
Normal force, can adopt any value needed to match the acceleration of the mass, according to Newton's 2nd Law.
Gravity (which we call weight near the Earth's surface) can be calculated as follows:

$F_{g} = m*g = 95 kg * 9.8 m/s2 = 930 N (1)$

According to Newton's 2nd Law, it must be met the following condition:

$F_{net} = F_{g} -F_{n} = m*a\\ F_{net} = 930 N - 830 N = 100 N = 95 Kg * a$

As the gravity is larger than normal force, this means that the acceleration is downward, so, we choose this direction as the positive.

Solving for a, we get:

$a =\frac{F_{net} }{m} =\frac{100 N}{95 kg} = 1.05 m/s2$

We can find the speed after the first 3.8 s (assuming a is constant), applying the definition of acceleration as the rate of change of velocity:

$v_{f} = a* t = 1.05 m/s * 3.8 m/s = 4.0 m/s$

Now, if during the next 3.8 s, normal force is 930 N (same as the weight), this means that both forces are equal each other, so net force is 0.
According to Newton's 2nd Law, if net force is 0, the object is either or at rest, or moving at a constant speed.
As the elevator was moving, the only choice is that it is moving at a constant speed, the same that it had when the scale was read for the first time, i.e., 4 m/s downward.

3 0

3 years ago

The emission of x rays can be described as an inverse photoelectric effect.

timama [110]

Answer:

The potential difference through which an electron accelerates to produce x rays is $1.24\times 10^4\ volts$ .

Explanation:

It is given that,

Wavelength of the x -rays, $\lambda=0.1\ nm=0.1\times 10^{-9}\ m$

The energy of the x- rays is given by :

$E=\dfrac{hc}{\lambda}$

The energy of an electron in terms of potential difference is given by :

$E=eV$

So,

$\dfrac{hc}{\lambda}=eV$

V is the potential difference

e is the charge on electron

$V=\dfrac{hc}{e\lambda}$

$V=\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{1.6\times 10^{-19}\times 0.1\times 10^{-9}}$

V = 12431.25 volts

$V=1.24\times 10^4\ volts$

So, the potential difference through which an electron accelerates to produce x rays is $1.24\times 10^4\ volts$ . hence, this is the required solution.

4 0

3 years ago