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Kruka [31]
4 years ago
9

Assume that, when we walk, in addition to a fluctuating vertical force, we exert a periodic lateral force of amplitude 25 n at a

frequency of about 1 hz. given that the mass of the bridge is about 2000 kg per linear meter, how many people were walking along the 144-m-long central span of the bridge at one time, when an oscillation amplitude of 75 mm was observed in that section of the bridge? take the damping constant to be such that the amplitude of the undriven oscillations would decay to 1/e of its original value in a time t=6t, where t is the period of the undriven, undamped system. express your answer numerically to three significant figures.
Physics
1 answer:
icang [17]4 years ago
8 0
There were 1810 number of people walking.
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Water drops from the nozzle of a shower onto the floor 81 inches below. The drops fall at regular intervals of time, the first d
Alexxx [7]

Answer:

0.91437 m

0.22859 m

Explanation:

g = Acceleration due to gravity = 9.81 m/s² = a

s=81\ inches=81\times 0.0254=2.0574\ m

s=ut+\frac{1}{2}at^2\\\Rightarrow 2.0574=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow t=\sqrt{\frac{2.0574\times 2}{9.81}}\\\Rightarrow t=0.64764\ s

When the time intervals are equal, if four drops are falling then we have 3 time intervals.

So, the time interval is

t'=\dfrac{t}{3}\\\Rightarrow t'=\dfrac{0.64764}{3}\\\Rightarrow t'=0.21588\ s

For second drop time is given by

t''=2t'\\\Rightarrow t''=2\times 0.21588\\\Rightarrow t''=0.43176\ s

Distance from second drop

s=ut+\dfrac{1}{2}at^2\\\Rightarrow y''=ut''+\dfrac{1}{2}at''^2\\\Rightarrow s=0\times t+\dfrac{1}{2}\times 9.81\times 0.43176^2\\\Rightarrow s=0.91437\ m

Distance from second drop is 0.91437 m

Distance from third drop

s=ut+\dfrac{1}{2}at^2\\\Rightarrow y''=ut'+\dfrac{1}{2}at'^2\\\Rightarrow s=0\times t+\dfrac{1}{2}\times 9.81\times 0.21588^2\\\Rightarrow s=0.22859\ m

Distance from third drop is 0.22859 m

6 0
3 years ago
Last night, Shirley worked on her accounting homework for one and one half hours. During that time, she completed 6 problems. Wh
hodyreva [135]

Answer:

velocity in problems per hour = 4 per hour

so correct option is b. 4 per hour

Explanation:

given data

worked on  homework time = 1.5 hour

completed = 6 problems

to find out

What is the velocity in problems per hour

solution

we know that Shirley solve complete 6 accounting homework problem in 1.5 hour so her velocity  in problems per hour will be as

velocity in problems per hour =  \frac{complete\ problem}{time\ taken}   ..................1

put here value we will get

velocity in problems per hour =  \frac{6}{1.5}

velocity in problems per hour = 4 per hour

so correct option is b. 4 per hour

3 0
4 years ago
Read 2 more answers
Dwayne ‘The Rock’ Johnson needs to escape from the fourth floor of a burning building (in a movie). He ties a rope around his wa
ZanzabumX [31]

Answer:

Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s

Explanation:

Let's start out with finding the force acting downwards because of the mass of 'The Rock':

Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N

Now the problem also states that the kinetic friction of the desk in this problem is 370 N

Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N

Now lets use F = ma to calculate for the acceleration of the desk:

787.58 = 63 x acceleration

acceleration = 12.501 m/s

Finally, we can use the motion equation:

v^2 - u^2 = 2*a*s

here u = 0 m/s (since initial speed of the desk is 0)

a = 12.501 m/s

and s = 10 m

Solving this we get:

v^2 - 0 = 2 * 12.501 * 10

v = 15.812 m/s

Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at            15.812 m/s when the desk reaches the window.

5 0
4 years ago
A high-temperature gas is compared to the same gas at lower temperature. Which of the following statements is true?
ycow [4]

Answer:

I think it is C

Explanation:

If the temperature of a gas increases, the gas particles have a higher average speed as they gain kinetic energy. They collide more frequently with the walls of the container, which produces a bigger pressure.

7 0
3 years ago
How does the media influence our view of beauty and gender roles?
shepuryov [24]
<span>They try to tell us what to think is beautiful, like they never have fat idols</span>
4 0
3 years ago
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