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-BARSIC- [3]
3 years ago
11

How to solve these two questions? ​

Physics
1 answer:
hammer [34]3 years ago
3 0

1) See attached figure

The relationship between charge and current is:

i = \frac{Q}{t}

where

i is the current

Q is the charge

t is the time

Therefore, the current is the rate of change of the charge passing through a given point over time.

This means that for a graph of charge over time, the current is just equal to the slope of the graph.

For the graph in this problem:

- Between t = 0 and t = 2 s, the slope is

\frac{50-0}{2-0}=25 C/s

therefore the current is

i = 25 A

- Between t = 2 s and t = 6 s, the slope is

\frac{-50-(50)}{6-2}=-25 C/s

therefore the current is

i = -25 A

- Between t = 6 s and t = 8 s, the slope is

\frac{0-(-50)}{8-6}=25 C/s

therefore the current is

i = 25 A

The figure attached show these values plotted on a graph.

2) 15 \mu C

The previous equation can be rewritten as

Q = i t

This equation is valid if the current is constant: if the current is not constant, then the total charge is simply equal to the area under a current vs time graph.

Here we have the current vs time graph, so we gave to find the area under it.

The area of the first triangle is:

A_1 = \frac{1}{2}(0.001 s)(0.010 A)=5\cdot 10^{-6} C

While the area of the second square is

A_2 = (0.002 s - 0.001 s)(0.010 A)=1\cdot 10^{-5}C

So, the total area (and the total charge) is

Q=A_1 +A_2 = 5\cdot 10^{-6} + 1\cdot 10^{-5} = 1.5\cdot 10^{-5}C=1.5 \mu C

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3 years ago
How does the scientific meaning of the words work, energy, force and efficiency compare to their every day meaning? State the si
Gelneren [198K]

Answer:

Force

If you're taking classical physics, simply stated, a force is a push or a pull of some sort. But there is one other very important thing to understand about Force. A true Force is always an interaction (at least from a classical perspective). That means that forces always come in pairs. This is stated in Newton's Third Law (equal and opposite forces). Every action must have a reaction. This is required for all true forces. Another consequence of this is that force is a vector, meaning it has a magnitude and a direction. The action and reaction will always be opposite in direction.

A lot of people will say F=ma. This is true. However, it is important to keep in mind that this definition is a calculational tool. It is more precise to say the Sum of all forces=ma. The point is that ma is not a force. Forces are things like weight, tension, normal, friction, gravity, electrostatic, magnetic, and various other applied forces. The sum of forces on an object equals the product of its mass times its acceleration.

It is important to keep in mind that the force is on the object that accelerates. Another way to state this is that objects cannot accelerate themselves. You cannot push yourself back (or forwards). But if you push a heavy object like a desk forwards, then the desk can push you back.

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2 years ago
a sprinter with a mass of 80kg accelerates uniformly from 0 m/s to 9 m/s in 3 s. a.)what is the runners acceleration? b.) what i
Katyanochek1 [597]
Part A: 
Acceleration can be calculated by dividing the difference of the initial and final velocities by the given time. That is,
             a = (Vf - Vi) / t
where a is acceleration,
Vf is final velocity,
Vi is initial velocity, and
t is time

Substituting,
            a = (9 m/s - 0 m/s) / 3 s = 3 m/s²
<em>ANSWER: 3 m/s²</em>

Part B: 
From Newton's second law of motion, the net force is equal to the product of the mass and acceleration,
               F = m x a
where F is force,
m is mass, and 
a is acceleration

Substituting,
              F = (80 kg) x (3 m/s²) = 240 kg m/s² = 240 N

<em>ANSWER: 240 N </em>

Part C: 
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         d = V₀t + 0.5at²

Substituting,
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<em>ANSWER: d = 13.5 m</em>

3 0
3 years ago
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nalin [4]

Answer:

Option (D)

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3 0
3 years ago
Testing shows that a sample of wood from an artifact contains 25% of the
daser333 [38]

Answer:

The artifact is 11,460 years old.

<u>Explanation</u>:

Given that,

The half life of the carbon-14 is 5730  years and we are left with 255 of the sample of wood from an arti-fact.

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So totally after 2 half-life the sample reduces into 25%

That is (5730 +5730) years = 11460 years

5 0
3 years ago
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