Answer:

Explanation:
Recall the formula for acceleration:
, where
is final velocity,
is initial velocity, and
is elapsed time (change in velocity over this amount of time).
Let's look at our time vs velocity graph. At t=0 seconds, V=25 m/s. So her initial velocity is 25 m/s.
We want to find the acceleration during the first 5 seconds of motion. Well, looking at our graph, at t=5 seconds, isn't our velocity still 25 m/s? Therefore, final velocity is 25 m/s (for this period of 5 seconds).
We are only looking from t=0 seconds to t=5 seconds which is a total period of 5 seconds. Therefore, elapsed time is 5 seconds.
Substituting values in our formula, we have:

Alternative:
Without even worrying about plugging in numbers, let's think about what acceleration actually is! Acceleration is the change in velocity over a certain period of time. If we are not changing our velocity at all, we aren't accelerating! In the graph, we can see that we have a straight line from t=0 seconds to t=5 seconds, the interval we are worried about. This indicates that our velocity is staying the same! At t=0 seconds, we have a velocity of 25 m/s and that velocity stays the same until t=5 seconds. Even though we are moving, we haven't changed velocity, which means our average acceleration is zero!
Answer:
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Explanation:
On the Top right of your screen, theres a bell button. Click that and it will show all the notifications. it will also show if a person answered it.
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Hope this helped
A) The change in internal chemical energy is 
B) The time needed is 1 minute
Explanation:
First of all, we start by calculating the power output of you and the bike, given by:

where
F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed
v = 8.0 m/s is the velocity
Substituting,

The energy output is related to the power by the equation

where:
P = 640 W is the power output
E is the energy output
is the time elapsed
Solving for E,

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

B)
From the previous part, we found that in a time of
t = 30 min
the amount of internal chemical energy converted is

Here we want to find the time t' needed to convert an amount of chemical energy of

So we can setup the following proportion:

And solving for t',

Learn more about power and energy:
brainly.com/question/7956557
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Answer:
1.72 x 10³ N.
Explanation:
When a charge is split equally and placed at a certain distance , maximum electrostatic force is possible.
So the charges will be each equal to
31/2 = 15.5 x 10⁻⁶ C
F = K Q q / r²
= 
= 1.72 x 10³ N.
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