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zhuklara [117]
3 years ago
10

Please help, what's the efficiency of the two pulleys​

Physics
1 answer:
lutik1710 [3]3 years ago
5 0

Answer:20cm

Explanation:

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An object change in position according to its reference point is called
Flura [38]

Answer:

motion

Explanation:

i had an assignment on it!

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3 years ago
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Two concrete spans of a 380 m long bridge are
Mazyrski [523]

Answer:

4.163 m

Explanation:

Since the length of the bridge is

L = 380 m

And the bridge consists of 2 spans, the initial length of each span is

L_i = \frac{L}{2}=\frac{380}{2}=190 m

Due to the increase in temperature, the length of each span increases according to:

L_f = L_i(1+ \alpha \Delta T)

where

L_i = 190 m is the initial length of one span

\alpha =1.2\cdot 10^{-5} ^{\circ}C^{-1} is the temperature coefficient of thermal expansion

\Delta T=20^{\circ}C is the increase in temperature

Substituting,

L_f=(190)(1+(1.2\cdot 10^{-5})(20))=190.0456 m

By using Pythagorean's theorem, we can find by how much the height of each span rises due to this thermal expansion (in fact, the new length corresponds to the hypothenuse of a right triangle, in which the base is the original length of the spand, and the rise in heigth is the other side); so we find:

h=\sqrt{L_f^2-L_i^2}=\sqrt{(190.0456)^2-(190)^2}=4.163 m

4 0
3 years ago
if the current in a wire is 2.0 amperes and the potential difference across the wire is 10 volts what is the resistance of the w
Pavlova-9 [17]

Answer:

R = 2Ω

Explanation:

Potential difference (V) = current (I) * Resistance (R)

V = IR

I = 2.0A

V = 10v

R = ?

V = IR

R = V / I

R = 10 / 2

R = 2Ω

The resistance across the wire is 2Ω

3 0
3 years ago
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. A 2.0-kg block is on a perfectly smooth ramp that makes an angle of 30° with the horizontal. (a) What is the block’s accelerat
AfilCa [17]

Answer:

a) a = 4.9 m / s²,  N = 16.97 N   and b)   F = 9.8 N

Explanation:

a) For this exercise we will use Newton's second law, we write a reference system with the x axis parallel to the plane, see attached, in this system the only force we have to break down is weight, let's use trigonometry

        sin 30 = Wx / W

        cos 30 = Wy / W

        Wx = W sin30

        Wy = W cos 30

Let's write the equations on each axis

X axis

        Wx = ma

Y Axis  

       N- Wy = 0

       N = Wy = mg cos 30

       N = 2.0 9.8 cos 30

       N = 16.97 N

We calculate the acceleration

       a = Wx / m

       a = mg sin 30 / m

       a = g sin 30

       a =9.8 sin 30

       a = 4.9 m / s²

b) For the block to move with constant speed, the acceleration must be zero, so the force applied must be equal to the weight component

      F -Wx = 0

      F = Wx

      F = m g sin 30

      F = 2.0 9.8 sin 30

      F = 9.8 N

5 0
3 years ago
A rifle fires a bullet into a giant slab of butter on a frictionless surface. The bullet penetrates the butter, but while passin
Vera_Pavlovna [14]

Answer:

V= 3.48 m/s

Explanation:

8 0
3 years ago
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