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Whitepunk [10]
3 years ago
14

In the vertical jump, an athlete starts from crouch and jumps upward to reach as high as possible. Even the best athletes spend

little more than 1.00s in the air (thier "hang time"). Treat the athlete as a particle and let ymax be his maximum height above the floor. To explain why he seems to hang in the air, calculate the ratio of the time he is above ymax /2 to the time it takes him to go from the floor to that height. You may ignore air resistance.

Physics
1 answer:
Mumz [18]3 years ago
3 0

Answer:

The ratio of the time he is above ymax /2 to the time it takes him to go from the floor to that height = 0.707

Explanation:

The mathematical derivation and steps is as shown in the attached file.

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To practice Problem-Solving Strategy 16.1 Standing waves. An air-filled pipe is found to have successive harmonics at 800 HzHz ,
bazaltina [42]

Answer:

Length of the pipe = 53.125 cm

Explanation:

given data

harmonic frequency f1  = 800 Hz

harmonic frequency f2  = 1120 Hz

harmonic frequency f3  = 1440 Hz

solution

first we get here fundamental frequency that  is express as

2F = f2 - f1    ...............1

put here value

2F = 1120 - 800

F = 160 Hz

and

Wavelength is express as

Wavelength  = Speed ÷ Fundamental frequency    ................2

here speed of waves in air  = 340 m/s

so put here value

Wavelength  =340 ÷ 160

Wavelength   = 2.125 m

so

Length of the pipe will be

Length of the pipe = 0.25 × wavelength    ......................3

put here value

Length of the pipe = 0.25 × 2.125

Length of the pipe = 0.53125 m

Length of the pipe = 53.125 cm

7 0
2 years ago
Opposition to a certain perspective can __________.
lisov135 [29]

Answer:

delay or stifle the emergence of the perspective

4 0
3 years ago
Please help me with this question, especially the angle part. I have solved the initial velocity already. I don't know what to d
Helga [31]
I think you almost got it.

At the top, the velocity only has horizontal component, so v=12 m/s is v_x, which is v*cos(theta), because v_x is constant, so the same when it was launched or now.

With the value of the initial speed (28 m/s, which is the total speed), you can set

v_x = v * cos( theta ) ---> 12 = 28*cos(theta) --> cos(theta)=12/28=3/7

or theta = 64.62 deg, it is D. Think about it. I hope you see it.
5 0
2 years ago
A running student has half the kinetic energy that his brother has. The student speeds up by 1 m/s, at which point he has the sa
hoa [83]

Answer:

V = (√2) + 1) m/s

Explanation:

Let the mass and speed of the running student be M and V respectively.

We are told that when he speeds up by 1 m/s, he has the same kinetic energy as his brother.

Thus, his speed at which he mow has the same kinetic energy as his brother is (V + 1) m/s

Now, we are told that the mass of the student is twice as large as that of his brother. Thus, his brother's mass is; M/2

Since kinetic energy is given by the formula K.E = ½mv²

Therefore, since we want to find the original speed of both students and that the initial condition says that the running student had half the kinetic energy of the brother, we now initial condition as;

½MV²= ½(½(M/2)V²) - - - - (eq 1)

Since he has sped up by 1 m/s, and has a kinetic energy now equal to that of his brother, we have;

(½M(V + 1)²) = (½(M/2)V²) - - - - (Eq2)

Dividing eq 1 by eq 2 gives;

V²/(V + 1)²= 1/2

Taking square root of both sides gives;

V/(V + 1) = 1/√2

Cross multiply to give;

(√2)V = V + 1

(√2)V - V = 1

V((√2) - 1) = 1

V = 1/((√2) - 1)

Simplifying this using surfs gives;

V = [1/((√2) - 1)] × ((√2) + 1))/((√2) + 1))

V = ((√2) + 1))/1

V = (√2) + 1) m/s

8 0
3 years ago
A stone is dropped from a height of 49m and simultaneously another ball is thrown upward from the ground with a speed of 40m/s.
Lilit [14]

Answer:

S1 = 1/2 g t^2     distance stone falls in time t

S2 = Vy t - 1/2 g t^2   distance thrown stone rises in time t

H = 49 = S1 + S2 = Vy t

t = 49 / 40 sec   time when stones meet

Check:

Stone 1 falls:      1/2 g t^2 = 1/2 * 9.8 * (49 / 40)^2 = 7.35 m

Stone 2 rises :  40 * (49 / 40) - 1/2 * 9.8 (49 / 40)^2 = 41.65 m

5 0
2 years ago
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