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Leya [2.2K]
3 years ago
10

Objectives

Physics
1 answer:
Lelu [443]3 years ago
4 0

Answer:

B

Explanation:

Given that an elevator moving down passes its neighbor, an elevator moving up. Their speed relative to one another is 8 m/s. What is the velocity of each elevator relative to someone standing on the first floor? Assume that the elevators are traveling at the same speed, and that the upward direction is

positive.

Solution

Given that upward direction is positive, then, the downward direction will be negative.

To get a relative velocity of 8m/s

4 - ( - 4 ) = 8

Therefore, the correct answer will be

One elevator is moving at 4 m/s; the other elevator is moving at -4 m/s

Which is option B

Because the negative multiply by negative sign will give positive sign.

Given

4 + 4 = 8.

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Answer:

First law: kinetic energy is used to turn an electric generator

Second law: some thermal energy is lost to the environment as it travels through the system

Explanation:

The first law of thermodynamics is known as the law of conservation of energy. It states that energy can neither be created nor destroyed but can only be transferred or changed from one form to another. When thermal energy is used to generate electricity, the kinetic energy of the steam is used to turn the electric generator (thereby producing electrical energy).

The second law of thermodynamics states that energy transfer or transformation leads to an increase in entropy resulting in the loss of energy. This law also states that as energy is transferred or transformed, some is lost in a form that is unusable. When thermal energy is used to generate electricity, some of the thermal energy is lost to the environment as it travels through the system.

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Material speed of light
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3 years ago
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An automobile starter motor has an equivalent resistance of 0.0500Ω and is supplied by a 12.0-V battery with a 0.0100-Ω internal
alexandr1967 [171]

Answer

given,

resistance = 0.05 Ω

internal resistance of battery = 0.01 Ω

electromotive force = 12 V

a) ohm's law

        V = IR

     and volage

   V = \epsilon - Ir

now,

   IR = \epsilon - Ir

   I(R+r) = \epsilon

   I= \dfrac{\epsilon}{R+r}

inserting the values

   I= \dfrac{12}{0.05+0.01}

      I = 200 A

b) Voltage

   V = I R

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   V = 10 V

c) Power

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d) total resistance = 0.05 + 0.09 = 0.14 Ω

 I= \dfrac{\epsilon}{R+r}

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6 0
3 years ago
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In a race, Usain Bolt accelerates at
jeka94

Answer:

65.87 s

Explanation:

For the first time,

Applying

v² = u²+2as.............. Equation 1

Where v = final velocity, u = initial velocity, a = acceleration, s = distance

From the question,

Given:  u = 0 m/s (from rest), a = 1.99 m/s², s = 60 m

Substitute these values into equation 1

v² = 0²+2(1.99)(60)

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t = (15.45-0)/1.99

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t = (v-u)/a

Given: v = 0 m/s(decelerates), u = 15.45 m/s, a = -0.266 m/s²

Substitute into the equation above

t = (0-15.45)/-0.266

t = 58.1 seconds

Hence total time taken to cover the distance

T = 7.77+58.1

T = 65.87 s

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Why is gravity an example of a scientific law?
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