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anzhelika [568]
3 years ago
5

Human muscles have an efficiency of about

Physics
1 answer:
ryzh [129]3 years ago
8 0

Answer: the answer is B. 18 to 26%

Explanation: I took the practice test on Edge and I got it right :)

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An elevator whose mass is m = 400 kilograms is supported by a cable. A frictional force of f = 80 newtons is applied to the elev
Dmitry_Shevchenko [17]

Answer:

3924 N

5124 N

4004 N

2884 N

4004 N

Explanation:

m = Mass of elevator = 400 kg

g = Acceleration due to gravity = 9.81 m/s²

a = Acceleration

f = Friction force = 80 N

When the elevator is stationary only the acceleration due to gravity will be acting on it

Tension

T=mg\\\Rightarrow T=400\times 9.81\\\Rightarrow T=3924\ N

The tension is 3924 N

The balanced force equation would be

T-mg-f=ma\\\Rightarrow T=ma+mg+f\\\Rightarrow T=400\times 2.8+400\times 9.81+80\\\Rightarrow T=5124\ N

The tension is 5124 N

When velocity is constant acceleration is zero

T-mg-f=0\\\Rightarrow T=mg+f\\\Rightarrow T=400\times 9.81+80\\\Rightarrow T=4004\ N

The tension is 4004 N

T-mg-f=-ma\\\Rightarrow T=-ma+mg+f\\\Rightarrow T=-400\times 2.8+400\times 9.81+80\\\Rightarrow T=2884\ N

The tension would be 2884 N

When velocity is constant acceleration is zero

T-mg-f=0\\\Rightarrow T=mg+f\\\Rightarrow T=400\times 9.81+80\\\Rightarrow T=4004\ N

The tension is 4004 N

4 0
4 years ago
A piece of wood is floating in a bathtub. A second piece of wood sits on top of the first piece, and does not touch the water. I
Julli [10]

Answer:

D

Explanation:

7 0
4 years ago
A 13.0-V battery is connected in series with a switch, resistor and coil. If the circuit's time constant is 1.20 ´ 10-4 s and th
slavikrds [6]

Answer:

R = 5.20 Ω,    L = 6.24 10⁻⁴ H

Explanation:

The current in an RL circuit is

           I = \frac{E}{R} \ (1- e^{- t/ \tau } )

           τ = L / R

In the problem they indicate the value of the voltage, the current and the time constant, for which the resistance must be found

         

The stable current is when enough time has passed (t »τ) after closing the circuit, therefore the exponential term is very small and we can neglect it.

            I = E / R

            R = E / I

let's calculate

            R = 13.0 / 2.50

            R = 5.20 Ω

now with this value we can find the inductance of the coil

            τ = L / R

            L = τ  R

            L = 1.20 10⁻⁴   5.2

            L = 6.24 10⁻⁴ H

3 0
3 years ago
What is the difference between a learner’s license and an operator’s license?
Stells [14]
<span>A Learner’s license is available to those at least 15 years old that have passed the written and vision tests.
</span><span>An intermediate license, you must be 16 or 17 years old and you must have held a learner’s license for at least 12 months without receiving any traffic violations.</span>
5 0
3 years ago
If the tension remains constant and the frequency increases, what happens to the wavelength?
kakasveta [241]
<span>As frequency increases, wavelength decreases. Frequency and wavelength are inversely proportional. This basically means that when the wavelength is increased, the frequency decreases and vice versa</span>
7 0
3 years ago
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