Physics, 03.07.2019 15:00, woodfordmaliky

Work of 36 joules is done on ball a. it travels a certain distance and hits ball b. ball b, which was stationary, starts to move at 12 m/s. if this is an elastic collision, then what was the initial velocity of ball a? (both balls have a mass of 500 g. ignore changes due to friction.)

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answered: kordejah348

here collision between two balls is perfectly elastic collision

and the friction force is considered to be zero

now here we can say that momentum conservation is applicable here

$m_1v_{1i} + m_2v_{2i} = m_1v_{1f} + m_1v_{2f}$

here we know that two balls are of same mass then we can say

$m*v + m*0 = m_1v_{1f} + m_1v_{2f}$

divide whole equation by mass "m"

$v = v_{1f} + v_{2f}$

now it is also given that it is elastic collision between two balls

$v_{2f} - v_{1f} = v_{1i} - v_{2i}$

$v_{2f} - v_{1f} = v - 0$

now by solving the above two equations we have

$v_{2f} = v$

$v_{1f} = 0$

so here given that

$v_{2f} = v = 12 m/s$

so the initial speed of ball A was same as final speed of ball B which is given as 12 m/s.

So here final answer will be 12 m/s

answered: Guest

most voltage drop calculators want the distance between the source and destination. then internally, they double it so both the source and return wires are calculated. but you need to know which distance the calculator uses so you're not half of what you should be or double what you should be.

most circuit breakers will not take a #6 directly, so the electrician will have to splice on a smaller pigtail. you also have to upsize the grounding wire when you upsized the ungrounded (hot) wire (see note in 250.122). this will preclude using most cable assemblies, as a cable with #6 copper will most likely only have a #10 grounding conductor. you need a #6 grounding conductor if the circuit is 20a. a #8 cable is no better, as it will have a #10 grounding conductor too. but most 20a breakers will take a #8 directly.

in your related post, you didn't say what type of load this is. if it is a light or heater, voltage drop won't be a big issue. if this is a motor, the current needs are huge at startup and the voltage drop can pose a problem. if this is a motor, knowing if the motor is under much load during startup will answer the voltage drop effect (a saw is easier to start than a compressor).

answered: Guest

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

$p(t)=0.3t^2+6t+80$

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

$p(0)=0+0+80=80$

according to question, we have said that if the population has twice its initial population, then it becomes

$p(t)=2\times 80=160$

so, time taken to reach this above mentioned population is given by

$160=0.3t^2+6t+80\\\\160-80=0.3t^2+6t\\\\80=0.3t^2+6t\\\\0.3t^2+6t-80=0\\\\\text{using quadratic formula ,we get }\\\\t_{1,\: 2}=\frac{-60\pm \sqrt{60^2-4\cdot \: 3\cdot \: 800}}{2\cdot \: 3}\\\\t=-29.14\ and\ t=9.149$

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.

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Work of 36 joules is done on ball a. it travels a certain distance and hits ball b. ball b, which wa...