12. In which of the positions shown in the picture, will Joshua have both potential and kinetic energy?

Physics

1 answer:

Zielflug [23.3K]2 years ago

8 0

Answer:

Answer: D. Only R

Explanation:

The Principle Of Conservation Of Mechanical Energy

In the absence of friction, the total mechanical energy is conserved. That means that

Em=U+K is constant, being U the potential energy and K the kinetic energy.

At the top of the path (point Q), Joshua is at rest but his height is at a maximum. Thus his kinetic energy is zero.

At point P, Joshua is at the minimum level (potential energy zero) and his speed is at a maximum.

At point R, Joshua has some height and some speed which means he has both types of energy.

Answer: D. Only R

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The average angular acceleration is -2.628 rad/s²

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Counterclockwise = positive

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Given;

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$\alpha = \frac{\delta \theta}{\delta t}\\\\ \alpha =\frac{\theta _2 - \theta_ 1}{t}\\\\ \alpha =\frac{-2.19 -6.55}{20.9} \\\\ \alpha =\frac{-8.74}{20.9}\\\\ \alpha = -0.4182 \ rotation / s^2\\\\ \alpha = \frac{-0.4182 \ rotation}{s^2}*\frac{2\pi \ radian}{rotation}\\\\ \alpha = -2.628 \ rad/s^2$