1.Two skaters, Evelyn and Lily, face each other on near frictionless ice. Evelyn has a mass of 57.4 kg, and Lily has a mass of 4
1 answer:
Answer:
-1.67 m/s
Explanation:
We can solve this problem by using the law of conservation of momentum: in fact, since the system is isolated (no external forces, since the ice is frictionless), the total momentum of Evelyin and Lily must be conserved.
The total momentum before is zero, since they are both at rest:
The total momentum after is:
where
m = 48.3 kg is Lily's mass
M = 57.4 kg is Evelyin's mass
V = 1.4 m/s is Evelyn's velocity
v is the Lily's velocity
Since momentum is conserved,
And so
Solving for v, we find Lily's velocity:
And the negative sign indicates that her direction is opposite to Evelyn's direction.
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(Missing question is: which of the following statements are true?)
a) <span>A battery does work on electric charges to bring them to a position of higher electric potential energy so that they can flow through a circuit to a lower potential energy --> TRUE
That's true: the battery does the work to move the charges to one end of its terminal thus creating a potential difference between the two terminals. Then, when it is connected to the circuit, charges start to flow to the terminal at lower potential (through the circuit)
b) </span><span>the potential difference between the terminals of a battery, when no current flows to an external circuit, is referred to as the terminal voltage --> FALSE
This is false: when no current flows, it is called e.m.f. (electromotive force)
c) </span><span>the internal resistance of a battery decreases with decreasing temperature
--> TRUE
In fact, the dependence of a resistance with the temperature is:
</span>![R=R_0[1+\alpha (T-T_0)]](https://tex.z-dn.net/?f=R%3DR_0%5B1%2B%5Calpha%20%28T-T_0%29%5D)
with
being generally positive, therefore the value of the resistance is proportional to T, and when T decreases, R decreases as well.
<span>d) a battery is a device that produces electricity by transforming chemical energy into electrical energy --> TRUE
</span><span>That's true: a battery uses chemical reactions to create a potential difference between the two terminals that can be exploited to make charges flowing through a circuit.
</span>
a) <span>A battery does work on electric charges to bring them to a position of higher electric potential energy so that they can flow through a circuit to a lower potential energy --> TRUE
That's true: the battery does the work to move the charges to one end of its terminal thus creating a potential difference between the two terminals. Then, when it is connected to the circuit, charges start to flow to the terminal at lower potential (through the circuit)
b) </span><span>the potential difference between the terminals of a battery, when no current flows to an external circuit, is referred to as the terminal voltage --> FALSE
This is false: when no current flows, it is called e.m.f. (electromotive force)
c) </span><span>the internal resistance of a battery decreases with decreasing temperature
--> TRUE
In fact, the dependence of a resistance with the temperature is:
</span>
with
<span>d) a battery is a device that produces electricity by transforming chemical energy into electrical energy --> TRUE
</span><span>That's true: a battery uses chemical reactions to create a potential difference between the two terminals that can be exploited to make charges flowing through a circuit.
</span>