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2 years ago

14

A learner sets up a circuit to determine the conductivity of certain solids. What piece of apparatus is not required for the nex

t experiment ?
A. battery
B. light bulb
C. conducting wire
D. stopwatch

1 answer:

Lilit [14]2 years ago

4 0

It is D as u dont need a stop watch aft that

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Answer:

(A) It will take 22 sec to come in rest

(b) Work done for coming in rest will be 0.2131 J

Explanation:

We have given the player turntable initially rotating at speed of $33\frac{1}{3}rpm=33.333rpm=\frac{2\times 3.14\times 33.333}{60}=3.49rad/sec$

Now speed is reduced by 75 %

So final speed $\frac{3.49\times 75}{100}=2.6175rad/sec$

Time t = 5.5 sec

From first equation of motion we know that '

$\alpha =\frac{\omega -\omega _0}{t}=\frac{2.6175-3.49}{4}=-0.158rad/sec^2$

(a) Now final velocity $\omega =0rad/sec$

So time t to come in rest $t=\frac{0-3.49}{-0.158}=22sec$

(b) The work done in coming rest is given by

$\frac{1}{2}I\left ( \omega ^2-\omega _0^2 \right )=\frac{1}{2}\times 0.035\times (0^2-3.49^2)=0.2131J$

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<u>Answer:</u>

<em>The initial distance between the trains is 1450 m. </em>

<u>Explanation:</u>

In the question two trains are of equal length 400 m and moves at a uniform speed of 72 km/h. train A is moving ahead of train B. If the train B has to overtake train A it should accelerate.

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<em> $u=72 \times 5/18=20 m/s$ </em>

<em>Distance covered in accelerating phase $S=ut+1/2 at^2$ </em>

<em> $=20 \times 50+1/2 \times 1 \times 50^2$ </em>

<em> $=1000+1250=2250 m$ </em>

If a train is just behind another, the distance covered by the train located behind during overtaking phase will be equal to the sum of the lengths of the trains.

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