2. John, whose mass is 70 kg, rolls along the sidewalk on in-line skates at 5.55 m/sec towards his sister Sue whose mass is 50 kg coming towards him at a
velocity of 4.5 m/sec. John grabs Sue's hand and pulls her with him. Assuming a
frictionless surface, what is their velocity as they continue to roll down the
sidewalk?

Protons have a positive charge and, collectively, give an element its atomic number.

Answerthe energy required is 1.60 × 10⁻¹⁸ j, to three significant figures.explanationwe define electric potential as the ratio electric potential energy to the charge,    then the following gives us the potential difference,      the formula  may be on your formula sheet.the change in electric potential energy would be the energy that would needed to move it from point a to point b. solving for that, we get    using q = 8.00  × 10⁻¹⁹ c and  δv = 2.00 v, we get    the energy required is 1.60 × 10⁻¹⁸ j, to three significant figures.

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