The heating and cooling of molecules will make ____________________ change their state of matter.
1 answer:
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The work done on the sail is 600 J
Explanation:
The work done to lift the sail is equal to the gain in gravitational potential energy of the sail, therefore is:
where
m is the mass of the sail
g is the acceleration of gravity
(mg) is the weight of the sail
is the change in height of the sail
In this problem we have
mg = 150 N (weight)
Substituting, we find the work done:
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A) Time needed: 6.24 s
B) Time needed: 2.86 s
Explanation:
A)
In this part, we are told that the power if the engine is constant. The power of the engine is given by
where
W is the work done
t is the time
This means that the power of the engine is proportional to the work done, and therefore, to the kinetic energy of the car:
where m is the mass of the car and v its velocity.
SInce power is constant, we can write:
where:
is the time the car needs to accelerates to
is the time the car needs to accelerate to
Therefore, solving for ,
B)
First of all, we have to calculate the acceleration of the car. We can do it using the following equation:
where:
u = 0 is the initial velocity
is the final velocity
t = 1.40 s is the time elapsed
Substituting, we find the acceleration:
In this part, we are told that the force exerted by the engine is constant: according to Newton's second law, acceleration is proportional to the force,
This means that the acceleration is also constant.
Now we want to find how long the car takes to accelerate to a final velocity of
From an initial velocity of
u = 0
Using again the same suvat equation, and using the acceleration we found previously, we find:
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About power:
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