Physics, 20.11.2020 19:30 misrachel03

HELP ASAP HELP Two tennis balls of the same mass are served at different speeds: 30 m/s and 60 m/s. Which serve has more kinetic energy and by how much? Defend your answer. *

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Answer from: PaulJames

The second ball has four times as much kinetic energy as the first ball.

Explanation:

Kinetic Energy

Is the type of energy an object has due to its state of motion. It's proportional to the square of the speed.

The equation for the kinetic energy is:

$\displaystyle K=\frac{1}{2}mv^2$

Where:

m = mass of the object

v = speed at which the object moves

The kinetic energy is expressed in Joules (J)

Two tennis balls have the same mass m and are served at speeds v1=30 m/s and v2=60 m/s.

The kinetic energy of the first ball is:

$\displaystyle K_1=\frac{1}{2}m\cdot 30^2$

$\displaystyle K_1=\frac{1}{2}m\cdot 900$

K_1=450m

The kinetic energy of the second ball is:

$\displaystyle K_2=\frac{1}{2}m\cdot 60^2$

$\displaystyle K_2=\frac{1}{2}m\cdot 3600$

K_2=1800m

Being m the same for both balls, the second ball has more kinetic energy than the first ball.

To find out how much, we find the ratio:

$\displaystyle \frac{K_2}{K_1}=\frac{1800m}{450m}$

Simplifying:

$\displaystyle \frac{K_2}{K_1}=4$

The second ball has four times as much kinetic energy as the first ball.

Answer from: Quest

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).

Answer from: Quest

Ithink they do have the same properties just in less quantities i think

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HELP ASAP HELP Two tennis balls of the same mass are served at different speeds: 30 m/s and 60 m/s....

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