Identify why dissolving salt in water would be considered a physical change.

When an object is heated it contracts. a. true b. false

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?