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BARSIC [14]
4 years ago
15

77. There is a 250-m-high cliff at Half Dome in Yosemite National Park in California. Suppose a boulder breaks loose from the to

p of this cliff. (a) How fast will it be going when it strikes the ground? (b) Assuming a reaction time of 0.300 s, how long a time will a tourist at the bottom have to get out of the way after hearing the sound of the rock breaking loose (neglecting the height of the tourist, which would become negligible anyway if hit)? The speed of sound is 335.0 m/s on this day.
Physics
1 answer:
lisabon 2012 [21]4 years ago
8 0

Answer:70 m/s or 6.84 s

Explanation:

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Which two statements about an electric motor are true?
allochka39001 [22]

Options (b) and (d) are correct about an electric motor.

An electric motor is a device which coverts electrical energy into mechanical energy.It works on the principle that when a current carrying coil is placed in a magnetic field, it experiences torque. Because of that torque, the coil rotates and thus the electrical energy gets converted into mechanical (motion) energy.

7 0
3 years ago
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The frequency of a person's pendulum is 0.3204 Hz when at a location where g is known to be exactly 9.800 m/s^2.
wel

Answer:

A) g = 9.751 m/s², B)       h = 2.573 10⁴ m

Explanation:

The angular velocity of a pendulum is

           w = √ g / L

Angular velocity and frequency are related.

          w = 2π f

          f = 1 / 2π √ g / L

A) with the initial data we can look for the pendulum length

        L = 1 /4π²   g / f²

        L = 1 /4π²   9,800 / 0.3204²

        L = 2.4181 m

The length of the pendulum does not change, let's look for the value of g for the new location

        g = 4π² f²  L

        g = 4π² 0.3196²  2.4181

        g = 9.75096 m / s²

         g = 9.751 m/s²

B) The value of the acceleration of gravity can be found with the law of universal gravitation

           F = G m M / R_{e}²

And Newton's second law

           W = m g

           W = F

         G m M / R_{e}² = mg

         g = G M / R_{e}²

         R_{e}² = G M / g

Let's calculate

          R_{e}² = 6.67 10⁻¹¹ 5.98 10²⁴ /9.75096

          R = √ 4.0905 10¹³ = √ 40.9053 10¹²

          R = 6.395726 10⁶ m

The height above sea level is

         h = R - [tex]R_{e}[/tex

         h = (6.395726 -6.37) 10⁶

         h = 0.0257256 106

         h = 2.573 10⁴ m

7 0
4 years ago
PLZ help this should be super easy
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The answer is number (3) if am wrong am sry
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What are the parts of the scientific method?
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