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uranmaximum [27]
3 years ago
10

2. An athlete of average size is hanging from the end of a 20 m long rope, which has a mass of 4 kg and is attached to a hook in

the ceiling of a gym. If the athlete makes a sudden movement at the end of the rope, estimate how long it will take the disturbance to reach the hook.
Physics
1 answer:
a_sh-v [17]3 years ago
7 0

Answer:

  t = 0.319 s

Explanation:

With the sudden movement of the athlete a pulse is formed that takes time to move along the rope, the speed of the rope is given by

             v = √T/λ

Linear density is

           λ = m / L

           λ = 4/20

           λ = 0.2 kg / m

The tension in the rope is equal to the athlete's weight, suppose it has a mass of m = 80 kg

           T = W = mg

           T = 80 9.8

           T = 784 N

The pulse rate is

          v = √(784 / 0.2)

          v = 62.6 m / s

The time it takes to reach the hook can be searched with kinematics

          v = x / t

          t = x / v

          t = 20 / 62.6

          t = 0.319 s

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bearhunter [10]

Answer:

B = 38.2μT

Explanation:

By the Ampere's law you have that the magnetic field generated by a current, in a wire, is given by:

B=\frac{\mu_o I_r}{2\pi r}     (1)

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r: distance from the center of the cylinder, in which B is calculated

Ir: current for the distance r

In this case, you first calculate the current Ir, by using the following relation:

I_r=JA_r

J: current density

Ar: cross sectional area for r in the hollow cylinder

Ar is given by  A_r=\pi(r^2-R_1^2)

The current density is given by the total area and the total current:

J=\frac{I_T}{A_T}=\frac{I_T}{\pi(R_2^2-R_1^2)}

R2: outer radius = 26mm = 26*10^-3 m

R1: inner radius = 5 mm = 5*10^-3 m

IT: total current  = 4 A

Then, the current in the wire for a distance r is:

I_r=JA_r=\frac{I_T}{\pi(R_2^2-R_1^2)}\pi(r^2-R_1^2)\\\\I_r=I_T\frac{r^2-R_1^2}{R_2^2-R_1^2}  (2)

You replace the last result of equation (2) into the equation (1):

B=\frac{\mu_oI_T}{2\pi r}(\frac{r^2-R_1^2}{R_2^2-R_1^2})

Finally. you replace the values of all parameters:

B=\frac{(4\pi*10^{-7}T/A)(4A)}{2\PI (12*10^{-3}m)}(\frac{(12*10^{-3})^2-(5*10^{-3}m)^2}{(26*10^{-3}m)^2-(5*10^{-3}m)^2})\\\\B=3.82*10^{-5}T=38.2\mu T

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The amplitude of the wave would be 5 meters.
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How many meters are in 45 centimeters?
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Explanation:

100 CM = 1 m

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An asteroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid
Katena32 [7]

Answer:

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Explanation:

u = Initial velocity

v = Final velocity

s = Displacement

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\Delta KE=\frac{1}{2}m(v^2-u^2)\\\Rightarrow \Delta KE=\frac{1}{2}3.7\times 10^4(4500^2-7500^2)\\\Rightarrow \Delta KE=-666000000000\ J

Work done be the force is 666000000000 J

W=F\times s\\\Rightarrow F=\frac{W}{s}\\\Rightarrow F=\frac{-666000000000}{1.7\times 10^6}\\\Rightarrow F=-391764.71\ N

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A 0.2 kg baseball moving with a velocity of 20 m/s is struck by a bat. The baseball reverses its direction and moves with a velo
krek1111 [17]

Average force is 666.67 N

<u>Explanation:</u>

Given that :

m = Mass of the baseball = 0.2 kg

u = Initial velocity = 20 m/s  

v = Final velocity = 40 m/s

t = Time taken for change in velocity = 0.006 s

We know:

Force exerted = mass × acceleration = m ×a

Acceleration can be found by means of dividing the change in velocity measured in m/s by the time taken in seconds.

a = $\frac{v-u}{t} = $a = \frac{40-20}{0.006} = 3,333.3 m/s²

Now we have to find the force using the formula, F = mass × acceleration as,

F = 0.2 kg ×3333.3 ms⁻² = 666.67 N

7 0
3 years ago
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