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3 years ago

The element lithium has two stable isotopes, Li-6 and Li-7. How do the atomic structures of these two isotopes compare?

1 answer:

6 0

All isotopes of Li have 3 protons and 3 electrons, but isotopes different in # of neutrons. Li-7 means the nucleus has 3 protons + 4 neutrons = 7 atomic mass.
So A) is the correct answer.

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An ammeter is connected in series with a resistor of unknown resistance R and a DC power supply of known emf e. A student uses t

rosijanka [135]

Answer:

B:The actual power dissipated by the resistor is less than P because the ammeter had some resistance.

Explanation:

Here,power has been calculated using current I and total EMF \ε . So,P=EMF*current= ε I will represent total power dissipated in resistor and ammeter.

Now, this total power P has been dissipated in both resistor and ammeter. So, power dissipated in resistor must be less than P as some power is also dissipated in ammeter because it has non-zero resistance.

So, the answer is B:The actual power dissipated by the resistor is less than P because the ammeter had some resistance.

Note that option A,C and E are ruled out as they state power dissipated by resistor is greater than or equal to P which is false.

Also,option D is ruled out as ammeter is connected in series.

8 0

4 years ago

A car moving in a straight line starts at x = 0 at t = 0 . It passes the point x = 30.0 m with a speed of 10.0 m/s at t = 3.00 s

Bogdan [553]

Answer:

a) $v=20.3m/s$

b) $a=2.35m/s^2$

Explanation:

From the exercise we know:

$x_{1}=30m$ ; $v_{1}=10m/s$ ; $t_{1}=3s$

$x_{2}=375m$ ; $v_{2}=50m/s$ ; $t_{2}=20s$

The formula for average velocity is:

$v=\frac{x_{2}-x_{1}}{t_{2}-t_{1}}$

a) $v=\frac{375m-30m}{20s-3s}=20.3m/s$

The formula for average acceleration is:

$a=\frac{v_{2}-v_{1}}{t_{2}-t_{1}}$

b) $a=\frac{(50-10)m/s}{(20-3)s}=2.35m/s^2$

4 0

3 years ago

(URGENT PLS HELP)The diagram shows a wire between the poles of a magnet.

iragen [17]

Answer:

I think it's d) down the page

4 0

3 years ago

Read 2 more answers

Which of the following would have an effect on an object's mass?

ICE Princess25 [194]

None of the above

mass is measurement of how much stuff in inside something.
if you freeze or heat an object, you merely change the state of the object. the mass is conserved.
if you change the elevation, nothing happens to the mass. the stuff will not leave the object.
so it is None of the above

8 0

3 years ago

A locomotive is pulling 8 freight cars, each of which is loaded with the same amount of weight. The mass of each freight car (wi

nikitadnepr [17]

Answer:106560 N

Explanation:

Given

Let Tension between 2 and 3 car be $T_{23}$ and between 3 &4 is $T_{34}$