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Art [367]
3 years ago
15

A person stands on top of a tall building holding two rocks at a height of 50 meters. At the same moment, one rock is dropped fr

om rest while the other is thrown downwards with an initial velocity of 8.0 m/s. Neglecting air resistance, calculate how long after the first rock lands does the second rock strike the ground
Physics
1 answer:
labwork [276]3 years ago
3 0

Answer

The second rock will land 2.4s after the first rock

Explanation:

Given that

Height of the building s=50m

We assume that the first rock is acting with gravity so that a=9.81m/s

And initial velocity u=0

Applying the equation of motion

S=ut+1/2at²

50=0*t+1/2(9.81)t²

50=4.905t²

t²=50/4.905

t²=10.19

t=√10.19

t=3.19sec

For the second rock initial velocity u=8m/s and v=0 and a=9.81

Applying the equation of motion

v=u+at

0=8+9.81t

t=-8/9.81

t=0.81sec

Hence the second rock will land 2.4s after the first rock

I.e

3.19-0.81

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Since the electron dropped from an energy level i to the ground state by emitting a single photon, this photon has an energy of 1.41 × 10⁻¹⁸ Joules.

<h3>How to calculate the photon energy?</h3>

In order to determine the photon energy of an electron, you should apply Planck-Einstein's equation.

Mathematically, the Planck-Einstein equation can be calculated by using this formula:

E = hf

<u>Where:</u>

  • h is Planck constant.
  • f is photon frequency.

In this scenario, this photon has an energy of 1.41 × 10⁻¹⁸ Joules because the electron dropped from an energy level i to the ground state by emitting a single photon.

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4 0
2 years ago
An airplane has wings, each with area A, designed so that air flows over the top of the wing at 265 m/s and underneath the wing
exis [7]

Answer

given,

Pressure on the top wing = 265 m/s

speed of underneath wings = 234 m/s

mass of the airplane =  7.2 × 10³ kg

density of air =  1.29 kg/m³

using Bernoulli's equation

 P_1 + \dfrac{1}{2}\rho v_1^2 = P_2 + \dfrac{1}{2}\rho v_2^2

 \Delta P =\dfrac{1}{2}\rho (v_2^2-v_1^2)

 \Delta P =\dfrac{1}{2}\times 1.29\times (265^2-234^2)

 \Delta P =9977.5 Pa

Applying newtons second law

2 Δ P x A - mg = 0

A =\dfrac{mg}{2\Delta P}

A =\dfrac{7.2\times 10^3 \times 9.8}{2\times 9977.5}

    A = 3.53 m²

7 0
3 years ago
1. What is the average speed of a runner that<br> travels 100 meters in 9.7 seconds?
alexdok [17]

Answer:

10.30928 m/s

Explanation:

6 0
2 years ago
An airplane starts from rest and accelerates at 10.8 m/s2 . what is its speed at the end of a 400 m long runway?
Cloud [144]

The final speed of an airplane is v = 92.95 m/s

The rate of change of position of an object in any direction is known as speed i.e. in other word, Speed is measured as the ratio of distance to the time in which the distance was covered.

Solution-

Here given,

Acceleration a= 10.8 m/s2 .

Displacement (s)= 400m

Then to find final speed of airplane v=?

Therefore from equation of motion can be written as,

v²=u²+ 2as

where, u is initial speed, v is final speed ,a is acceleration and s is displacement of the airplane. Therefore by putting the value of a & s in above equation and (u =0) i.e. the initial speed of airplane is zero.

v²= 2×10.8 m/s²×400m

v²=8640m/s

v=92.95m/s

hence the final speed of airplane v =92.95m/s

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5 0
1 year ago
An assumption of learning curve theory is _________
nalin [4]

Answer:

Unit time will decrease

Explanation:

6 0
2 years ago
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