In the balloon and can experiment, why is it necessary to hold the balloon close to the can to get it to move? Use evidence and scientific reasoning to support your explanation.

1)The electrical charge on the balloon is the same as the charge of the can

2)The can is aluminum and aluminum is not magnetic.

3)The electrical charge on the balloon is opposite of the can.

4)The closer the can is to the balloon the stronger the charge will be.

If two students are running down the hall toward each other, trying to get to class, and they have the same mass and acceleration, what will happen when they collide? will their forces cancel out or will each one experience a reaction?

How does an observation about an object differ from an inference about that object

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.